Fix varargs bug/usage, found by Coverity Scan

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/build.yml

@@ -28,7 +28,7 @@ jobs:
         run: |
           sudo apt-get -y update
           sudo apt-get -y install tree doxygen
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Configure
         run: |
           ./autogen.sh
@@ -44,7 +44,7 @@ jobs:
         run: |
           make check || (cat test/test-suite.log; false)
       - name: Upload Test Results
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v3
         with:
           name: libite-test-${{ matrix.compiler }}
           path: test/*
@@ -55,7 +55,7 @@ jobs:
     env:
       MAKEFLAGS: -j3
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Installing dependencies
         run: |
           apt-get update

.github/workflows/coverity.yml

@@ -15,7 +15,7 @@ jobs:
   coverity:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Fetch latest Coverity Scan MD5
         id: var
         env:
@@ -24,10 +24,8 @@ jobs:
           wget -q https://scan.coverity.com/download/cxx/linux64         \
                --post-data "token=$TOKEN&project=${COVERITY_PROJ}&md5=1" \
                -O coverity-latest.tar.gz.md5
-          export MD5=$(cat coverity-latest.tar.gz.md5)
-          echo "Got MD5 $MD5"
-          echo ::set-output name=md5::${MD5}
-      - uses: actions/cache@v2
+          echo "md5=$(cat coverity-latest.tar.gz.md5)" | tee -a $GITHUB_OUTPUT
+      - uses: actions/cache@v3
         id: cache
         with:
           path: coverity-latest.tar.gz
@@ -76,7 +74,7 @@ jobs:
             --form description="${PROJECT_NAME} $(git rev-parse HEAD)" \
             https://scan.coverity.com/builds?project=${COVERITY_PROJ}
       - name: Upload build.log
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v3
         with:
           name: coverity-build.log
           path: cov-int/build-log.txt

.github/workflows/release.yml

@@ -7,38 +7,11 @@ on:
 
 jobs:
   release:
-    name: Create GitHub release
-    runs-on: ubuntu-latest
-    if: startsWith(github.ref, 'refs/tags/')
-    outputs:
-      upload_url: ${{ steps.create_release.outputs.upload_url }}
-      release_id: ${{ steps.create_release.outputs.id }}
-    steps:
-      - uses: actions/checkout@v2
-      - name: Extract ChangeLog entry ...
-        # Hack to extract latest entry for body_path below
-        run: |
-          awk '/-----*/{if (x == 1) exit; x=1;next}x' ChangeLog.md \
-              |head -n -1 > release.md
-          cat release.md
-      - name: Create release ...
-        id: create_release
-        uses: actions/create-release@v1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        with:
-          tag_name: ${{ github.ref }}
-          release_name: Libite (-lite) ${{ github.ref }}
-          body_path: release.md
-          draft: false
-          prerelease: false
-  tarball:
     name: Build and upload release tarball
-    needs: release
     if: startsWith(github.ref, 'refs/tags/')
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Installing dependencies ...
         run: |
           sudo apt-get -y update
@@ -46,17 +19,19 @@ jobs:
       - name: Creating Makefiles ...
         run: |
           ./autogen.sh
-          ./configure
+          ./configure --prefix=
       - name: Build release ...
         run: |
-          make release || (cat test/test-suite.log; false)
-          ls -lF ../
+          make release
           mkdir -p artifacts/
           mv ../*.tar.* artifacts/
-      - name: Upload release artifacts ...
-        uses: skx/github-action-publish-binaries@release-0.15
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Extract ChangeLog entry ...
+        run: |
+          awk '/-----*/{if (x == 1) exit; x=1;next}x' ChangeLog.md \
+              |head -n -1 > release.md
+          cat release.md
+      - uses: ncipollo/release-action@v1
         with:
-          releaseId: ${{ needs.release.outputs.release_id }}
-          args: artifacts/*
+          name: Libite (-lite) ${{ github.ref_name }}
+          bodyFile: "release.md"
+          artifacts: "artifacts/*"

ChangeLog.md

@@ -4,6 +4,22 @@ Change Log
 All notable changes to the project are documented in this file.
 
 
+[v2.6.0][UNRELEASED]
+--------------------
+
+### Changes
+- New APIs from the [Infix Project](https://github.com/kernelkit/infix):
+  - `fexistf()`
+  - `vfopenf()`
+  - `popenf()`
+  - `vreadsnf()`, `readsnf()`, `writesf()`
+  - `vreadllf()`, `readllf()`, `readdf()`
+  - `writellf()`, `writedf()`
+
+### Fixes
+- Spellchecking of API docs
+
+
 [v2.5.3][] - 2023-04-08
 -----------------------
 
@@ -488,7 +504,9 @@ problems this may cause!
 Initial extraction of frog DNA from [Finit][].  See [README][] for API details.
 
 
-[UNRELEASED]: https://github.com/troglobit/libite/compare/v2.5.2...HEAD
+[UNRELEASED]: https://github.com/troglobit/libite/compare/v2.5.3...HEAD
+[v2.6.0]: https://github.com/troglobit/libite/compare/v2.5.3...v2.6.0
+[v2.5.3]: https://github.com/troglobit/libite/compare/v2.5.2...v2.5.3
 [v2.5.2]: https://github.com/troglobit/libite/compare/v2.5.1...v2.5.2
 [v2.5.1]: https://github.com/troglobit/libite/compare/v2.5.0...v2.5.1
 [v2.5.0]: https://github.com/troglobit/libite/compare/v2.4.1...v2.5.0

LICENSE

@@ -1,5 +1,5 @@
 Copyright (c) 2008-2010  Claudio Matsuoka <cmatsuoka@gmail.com>
-Copyright (c) 2008-2021  Joachim Wiberg <troglobit@gmail.com>
+Copyright (c) 2008-2023  Joachim Wiberg <troglobit@gmail.com>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

TODO.org

@@ -0,0 +1 @@
+* TODO Write tests for new APIs

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT(libite, 2.5.3, https://github.com/troglobit/libite/issues)
+AC_INIT(libite, 2.6.0-rc1, https://github.com/troglobit/libite/issues)
 AC_CONFIG_AUX_DIR(aux)
 AM_INIT_AUTOMAKE([1.11 foreign dist-xz])
 AM_SILENT_RULES([yes])

debian/changelog

@@ -1,3 +1,16 @@
+libite (2.6.0) stable; urgency=medium
+
+  * New APIs from Infix Project:
+    - fexistf()
+    - vfopenf()
+    - popenf()
+    - vreadsnf(), readsnf(), writesf()
+    - vreadllf(), readllf(), readdf()
+    - writellf(), writedf()
+  * Spellchecking of API docs
+
+ -- Joachim Wiberg <troglobit@gmail.com>  Sun, 17 Sep 2023 12:16:47 +0200
+
 libite (2.5.3) stable; urgency=medium
 
  * rsync() does not copy single files correctly

doc/API.md

@@ -124,7 +124,7 @@ Generic Functions
 
   Check for the existence of a directory, returns True(1) or False(0).
 
-- `fopenf(mode, fmt, ...)`
+- `fopenf(mode, fmt, ...)` and `vfopenf(mode, fmt, ap)`
 
   Like `fopen()`, but takes a formatted string as argument.  This
   greatly simplifies operations that usually consist of composing a
@@ -249,6 +249,19 @@ Generic Functions
   `delete`, it is now called `opt`.  The APIs are 100% compatible if the
   value `1` was used.
 
+- `runbg(cmd, delay)`
+
+  Run a command in the background, after delay microseconds, essentially
+  a background `execvp()` with a delay.  The function employs double-fork
+  to prevent zombies and closes all open files, including stdio.
+  
+```C
+    char *cmd[] = { "sh", "-c", "echo 'hej' >/tmp/foo", NULL};
+
+    runbg(cmd, 200000); /* Create /tmp/foo after 200 millisec */
+    /* Execution continues here immediately */
+```
+
 - `strmatch(str, list)`, `strnmatch(str, list, len)`
 
   Find matching string in an array of strings.  Returns index in array on
@@ -307,6 +320,76 @@ Generic Functions
   yes (both `y` and `Y` are handled) and `FALSE` for everything else.
 
 
+Procfile Functions
+------------------
+
+These functions can be used to simplify access to data in `/proc` and
+`/sys` on a Linux system.
+
+### String Functions
+
+- `readsnf(line, len, fmt, ...)`
+
+  Read first line from a file composed from `fmt`, with optional args.
+  At most `len` bytes from the file are stored in `line`.
+
+  On success this function returns `line` with any trailing newlines
+  `chomp()`ed off.  On error `NULL` is returned.
+
+- `vreadsnf(line, len, fmt, ap)`
+
+  Similar to `readsnf()` but takes a `va_list` argument instead.
+
+- `writesf(str, mode, fmt, ...)`
+
+  Write the string buffer `str`, with an additional newline, to a file
+  composed from `fmt`, with optional args.  The file is opened with the
+  given `mode`, e.g. "w+", which allows for both replacing and appending
+  file content.
+
+  The function returns POSIX OK(0) on success or -1 on failure with the
+  `errno` variable set to a value from either `fopen()` or `fclose()`.
+
+### Integer Functions
+
+Read and write 32-bit and 64-bit signed values from/to files.
+
+- `vreadllf(value, fmt, ap)` and `readllf(value, fmt, ...)`
+
+  Only the first line is read.  If the line has newline that is stripped
+  before calling `strtoll()` on the line.  The arguments to the latter
+  function is such that it can convert also from a hexadecimal value.
+
+  This function may fail and return -1 on opening the file, reading a
+  line, or if the `strtoll()` function fails.  All of which set the
+  `errno` variable.  Otherwise this function return POSIX OK(0).
+
+- `readdf(value, fmt, ...)`
+
+  Read a signed 32-bit value from a file composed from `fmt`, with
+  optional args.  This function use `vreadllf()` with an additional
+  range checking for `INT_MIN` and `INT_MAX`.  Values outside that
+  cause this function to return -1 with `errno` set to `ERANGE`.
+
+- `writedf(value, mode, fmt, ...)`
+
+  Write a signed 32-bit `value` to a file composed from `fmt`, with
+  optional args.  The file is opened with the given `mode`, e.g. "w+",
+  which allows for both replacing and appending file content.
+
+  The function returns POSIX OK(0) on success or -1 on failure with the
+  `errno` variable set to a value from either `fopen()` or `fclose()`.
+
+- `writellf(value, mode, fmt, ...)`
+
+  Write a signed 64-bit `value` to a file composed from `fmt`, with
+  optional args.  The file is opened with the given `mode`, e.g. "w+",
+  which allows for both replacing and appending file content.
+
+  The function returns POSIX OK(0) on success or -1 on failure with the
+  `errno` variable set to a value from either `fopen()` or `fclose()`.
+
+
 GNU Functions
 -------------
 

src/Makefile.am

@@ -2,21 +2,21 @@ lib_LTLIBRARIES       = libite.la
 
 libite_la_CPPFLAGS    = -D_GNU_SOURCE
 libite_la_CFLAGS      = -W -Wall -Wextra
-libite_la_LDFLAGS     = $(AM_LDFLAGS) -version-info 8:2:3
+libite_la_LDFLAGS     = $(AM_LDFLAGS) -version-info 9:0:4
 libite_la_SOURCES     = chomp.c		copyfile.c			\
 			conio.c		conio.h		dir.c		\
 			erasef.c	fopenf.c	fremove.c	\
 			fexist.c	fisdir.c			\
 			fparseln.c	fsendfile.c			\
 			ifconfig.c	lfile.c				\
-			makepath.c	progress.c			\
-			pidfile.c	pidfilefn.c			\
-			reallocarray.c	rsync.c		strtrim.c	\
+			makepath.c	procval.c	progress.c	\
+			pidfile.c	pidfilefn.c	popenf.c	\
+			reallocarray.c	rsync.c		runbg.c		\
 			strlcpy.c 	strlcat.c 	strtonum.c	\
 			strdupa.h	strndupa.h	strnlen.h	\
-			strmatch.c	systemf.c	touchf.c	\
+			strmatch.c	systemf.c	strtrim.c	\
 			telnet.c	tempfile.c	truncatef.c	\
-			yorn.c		which.c				\
+			touchf.c	yorn.c		which.c		\
 			lite.h		strlite.h			\
 			queue.h		tree.h
 

src/fexist.c

@@ -29,8 +29,13 @@
  */
 
 #include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
 #include <unistd.h>
 
+#include "lite.h"
+
 /**
  * Check if a file exists in the file system.
  * @param file File to look for, with full path.
@@ -50,6 +55,39 @@ int fexist(const char *file)
 	return 1;
 }
 
+/**
+ * Like fexist() but with formatted string support
+ * @param fmt  Formatted string to be composed into the file to look for.
+ *
+ * This is a wrapper for the fexist() function in lite.h, lessening the
+ * burden of having to compose the filename from parts in a seprate
+ * buffer.
+ *
+ * @returns @c TRUE(1) if the @a file exists, otherwise @c FALSE(0).
+ */
+int fexistf(const char *fmt, ...)
+{
+	va_list ap;
+	char *file;
+	int len;
+
+	va_start(ap, fmt);
+	len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+
+	file = alloca(len + 1);
+	if (!file) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	va_start(ap, fmt);
+	vsnprintf(file, len + 1, fmt, ap);
+	va_end(ap);
+
+	return fexist(file);
+}
+
 /**
  * Local Variables:
  *  indent-tabs-mode: t

src/fopenf.c

@@ -27,10 +27,43 @@
 #include <stdarg.h>
 #include <stdlib.h>
 
+/**
+ * Similar to fopenf() except it takes a @a va_list argument
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
+ * @param ap   List of variable arguemnts from va_start().
+ *
+ * See fopenf() for details.
+ *
+ * @returns a FILE pointer, or @c NULL on error.
+ */
+FILE *vfopenf(const char *mode, const char *fmt, va_list ap)
+{
+	va_list apc;
+	char *file;
+	int len;
+
+	va_copy(apc, ap);
+	len = vsnprintf(NULL, 0, fmt, apc);
+	va_end(apc);
+
+	file = alloca(len + 1);
+	if (!file) {
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	va_copy(apc, ap);
+	vsnprintf(file, len + 1, fmt, apc);
+	va_end(apc);
+
+	return fopen(file, mode);
+}
+
 /**
  * Open a file based on the formatted string and optional arguments
- * @param mode An fopen() mode string, e.g. "w+"
- * @param fmt  Formatted string to be composed into a pathname
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
  *
  * This function is an extension to the fopen() family, lessening the burden
  * of first having to compose the filename from parts in a seprate buffer.
@@ -42,24 +75,15 @@
 FILE *fopenf(const char *mode, const char *fmt, ...)
 {
 	va_list ap;
-	char *file;
-	int len;
+	FILE *fp;
 
 	va_start(ap, fmt);
-	len = vsnprintf(NULL, 0, fmt, ap);
+	fp = vfopenf(mode, fmt, ap);
 	va_end(ap);
-
-	file = alloca(len + 1);
-	if (!file) {
-		errno = ENOMEM;
+	if (!fp)
 		return NULL;
-	}
 
-	va_start(ap, fmt);
-	vsnprintf(file, len + 1, fmt, ap);
-	va_end(ap);
-
-	return fopen(file, mode);
+	return fp;
 }
 
 /**

src/lite.h

@@ -1,7 +1,7 @@
 /* Collection of frog DNA
  *
  * Copyright (c) 2008-2010  Claudio Matsuoka <cmatsuoka@gmail.com>
- * Copyright (c) 2008-2021  Joachim Wiberg <troglobit@gmail.com>
+ * Copyright (c) 2008-2023  Joachim Wiberg <troglobit@gmail.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -26,7 +26,7 @@
  * Collection of frog DNA
  * @file lite.h
  * @author Claudio Matsuoka (2008-2010)
- * @author Joachim Wiberg (2008-2021)
+ * @author Joachim Wiberg (2008-2023)
  * @copyright MIT License
  *
  * The latest version of this manual and the libite (-lite) software
@@ -77,8 +77,10 @@ int     erasef     (const char *fmt, ...) __attribute__ ((format (printf, 1, 2))
 char   *fparseln   (FILE *, size_t *, size_t *, const char[3], int);
 
 int     fexist     (const char *file);
+int     fexistf    (const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));;
 int     fisdir     (const char *path);
 
+FILE   *vfopenf    (const char *mode, const char *fmt, va_list ap);
 FILE   *fopenf     (const char *mode, const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
 int     fremove    (const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 FILE   *tempfile   (void);
@@ -88,6 +90,16 @@ int     fcopyfile  (FILE *src, FILE *dst);
 ssize_t fsendfile  (FILE *src, FILE *dst, size_t len);
 int     truncatef  (off_t length, const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
 
+char   *vreadsnf   (char *line, size_t len, const char *fmt, va_list ap);
+char   *readsnf    (char *line, size_t len, const char *fmt, ...);
+int     writesf    (const char *str, const char *mode, const char *fmt, ...);
+
+int     vreadllf   (long long *value, const char *fmt, va_list ap);
+int     readllf    (long long *value, const char *fmt, ...);
+int     readdf     (int *value, const char *fmt, ...);
+int     writellf   (long long value, const char *mode, const char *fmt, ...);
+int     writedf    (int value, const char *mode, const char *fmt, ...);
+
 int     ifconfig   (const char *ifname, const char *addr, const char *mask, int up);
 
 lfile_t*lfopen     (const char *file, const char *sep);
@@ -104,6 +116,8 @@ int     makepath   (const char *dir);
 int     dir        (const char *dir, const char *type, int (*filter) (const char *file), char ***list, int strip);
 int     rsync      (char *src, char *dst, int opt,  int (*filter) (const char *file));
 
+FILE   *popenf     (const char *type, const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
+
 int     pidfile       (const char *basename);
 int     pidfile_signal(const char *pidfile, int signal);
 pid_t   pidfile_read  (const char *pidfile);
@@ -114,6 +128,7 @@ void   *reallocarray(void *optr, size_t nmemb, size_t size);
 void    progress       (int percent, int max_width);
 void    progress_simple(int percent);
 
+int     runbg          (char *const cmd[], int delay);
 int     systemf        (const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 
 sdbuf_t*telnet_open    (int addr, short port);

src/popenf.c

@@ -0,0 +1,63 @@
+/* Formatted popen()
+ *
+ * Copyright (c) 2023  Tobias Waldekranz <tobias@waldekranz.com>
+ * Copyright (c) 2023  Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+/**
+ * Formatted pipe stream to or from a process
+ * @param type A popen() type, "r" or "w", can also include "e" for @c O_CLOEXEC.
+ * @param fmt  Formatted string to be composed into a shell command line.
+ *
+ * This function is an extension to popen(), lessening the burden of
+ * first having to compose the filename from parts in a seprate buffer.
+ *
+ * @returns Upon successful completion, popenf() returns a FILE pointer.
+ * Otherwise, @c NULL is returned and @a errno is set to indicate the
+ * error.
+ */
+FILE *popenf(const char *type, const char *fmt, ...)
+{
+	va_list ap;
+	char *cmd;
+	int len;
+
+	va_start(ap, fmt);
+	len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+
+	cmd = alloca(len + 1);
+	if (!cmd) {
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	va_start(ap, fmt);
+	vsnprintf(cmd, len + 1, fmt, ap);
+	va_end(ap);
+
+	return popen(cmd, type);
+}

src/procval.c

@@ -0,0 +1,229 @@
+/* Reading and writing values/strings to/from /proc and /sys style files
+ *
+ * Copyright (c) 2023  Tobias Waldekranz <tobias@waldekranz.com>
+ * Copyright (c) 2023  Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/**
+ * @file procval.c
+ * @author Joachim Wiberg
+ * @date 2023
+ * @copyright ISC License
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "lite.h"
+
+/**
+ * Similar to readsnf() except it takes a @a va_list argument
+ * @param line Pointer to line buffer.
+ * @param len  Size of line buffer.
+ * @param fmt  Formatted string to be composed into a pathname.
+ * @param ap   List of variable arguemnts from va_start().
+ *
+ * For details, see readsnf().
+ *
+ * @returns same as readsnf().
+ */
+char *vreadsnf(char *line, size_t len, const char *fmt, va_list ap)
+{
+	va_list apc;
+	FILE *fp;
+
+	va_copy(apc, ap);
+	fp = vfopenf("r", fmt, apc);
+	va_end(apc);
+	if (!fp)
+		return NULL;
+
+	if (!fgets(line, len, fp)) {
+		fclose(fp);
+		return NULL;
+	}
+
+	fclose(fp);
+	return chomp(line);
+}
+
+
+/**
+ * Read first line from a file composed from fmt and optional args.
+ * @param line Pointer to line buffer.
+ * @param len  Size of line buffer.
+ * @param fmt  Formatted string to be composed into a pathname.
+ *
+ * @returns On success, this function returns the @p line read from the
+ * file, with any trailing '\n' chomp()ed out.  On error, @c NULL.
+ */
+char *readsnf(char *line, size_t len, const char *fmt, ...)
+{
+	va_list ap;
+	char *ln;
+
+	va_start(ap, fmt);
+	ln = vreadsnf(line, len, fmt, ap);
+	va_end(ap);
+
+	return ln;
+}
+
+/**
+ * Write a string buffer to a file composed from fmt and optional args.
+ * @param str  Pointer to string buffer, may be multiple lines.
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
+ *
+ * @returns result of operation, with @a errno set on error.
+ */
+int writesf(const char *str, const char *mode, const char *fmt, ...)
+{
+	va_list ap;
+	FILE *fp;
+
+	va_start(ap, fmt);
+	fp = vfopenf(mode, fmt, ap);
+	va_end(ap);
+	if (!fp)
+		return -1;
+
+	fprintf(fp, "%s\n", str);
+	return fclose(fp);
+}
+
+/**
+ * Same as readllf() except it takes a @a va_list argument.
+ */
+int vreadllf(long long *value, const char *fmt, va_list ap)
+{
+	char line[0x100];
+
+	if (!vreadsnf(line, sizeof(line), fmt, ap))
+		return -1;
+
+	errno = 0;
+	*value = strtoll(line, NULL, 0);
+
+	return errno ? -1 : 0;
+}
+
+/**
+ * Read 64-bit integer value from a file composed from fmt and optional args.
+ * @param value Pointer to where to store read 64-bit integer value.
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
+ *
+ * @returns result of operation, with @a errno set on error.
+ */
+int readllf(long long *value, const char *fmt, ...)
+{
+	va_list ap;
+	int rc;
+
+	va_start(ap, fmt);
+	rc = vreadllf(value, fmt, ap);
+	va_end(ap);
+
+	return rc;
+}
+
+
+/**
+ * Read integer value from a file composed from fmt and optional args.
+ * @param value Pointer to where to store read integer value.
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
+ *
+ * @returns result of operation, with @a errno set on error.
+ */
+int readdf(int *value, const char *fmt, ...)
+{
+	long long tmp;
+	va_list ap;
+	int rc;
+
+	va_start(ap, fmt);
+	rc = vreadllf(&tmp, fmt, ap);
+	va_end(ap);
+
+	if (rc)
+		return rc;
+
+	if (tmp < INT_MIN || tmp > INT_MAX) {
+		errno = ERANGE;
+		return -1;
+	}
+
+	*value = tmp;
+	return 0;
+}
+
+/**
+ * Write 64-bit integer value to a file composed from fmt and optional args.
+ * @param value 64-bit integer value to write.
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
+ *
+ * @returns result of operation, with @a errno set on error.
+ */
+int writellf(long long value, const char *mode, const char *fmt, ...)
+{
+	va_list ap;
+	FILE *fp;
+
+	va_start(ap, fmt);
+	fp = vfopenf(mode, fmt, ap);
+	va_end(ap);
+	if (!fp)
+		return -1;
+
+	fprintf(fp, "%lld\n", value);
+	return fclose(fp);
+}
+
+
+/**
+ * Write integer value to a file composed from fmt and optional args.
+ * @param value Integer value to write.
+ * @param mode An fopen() mode string, e.g. "w+".
+ * @param fmt  Formatted string to be composed into a pathname.
+ *
+ * @returns result of operation, with @a errno set on error.
+ */
+int writedf(int value, const char *mode, const char *fmt, ...)
+{
+	va_list ap;
+	FILE *fp;
+
+	va_start(ap, fmt);
+	fp = vfopenf(mode, fmt, ap);
+	va_end(ap);
+	if (!fp)
+		return -1;
+
+	fprintf(fp, "%d\n", value);
+	return fclose(fp);
+}
+
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

src/runbg.c

@@ -0,0 +1,93 @@
+/* Run a command in the background: fork() + usleep() + execvp()
+ *
+ * Copyright (c) 2023  Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/**
+ * @file runbg.c
+ * @author Joachim Wiberg
+ * @date 2023
+ * @copyright ISC License
+ */
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/**
+ * Run command in the background
+ * @param cmd    NULL terminated list of command and optional arguments
+ * @param delay  Microseconds after fork() to wait before calling cmd
+ *
+ * This function forks to run the given command @p cmd in the background.
+ * To ensure there are no lingering zombies the function actuall forks
+ * twice, and also calls setsid(), before it calls usleep() with the @p
+ * delay argument.  The command @p cmd is handed over to execvp().
+ *
+ * Since it runs in the background it is not possible to get the return
+ * code of the command.
+ *
+ * @returns on successful (first) fork(), this function returns POSIX
+ * OK(0), otherwise -1 and @a errno is set to indicate the error.
+ */
+int runbg(char *const cmd[], int delay)
+{
+	int pid = fork();
+	int rc;
+
+	if (!pid) {
+		int fd, maxfd;
+
+		if (setsid() == -1)
+			_exit(errno);
+
+		/* reparent to init */
+		pid = fork();
+		if (pid == -1)
+			_exit(errno);
+		if (pid > 0)
+			_exit(0);
+
+		maxfd = sysconf(_SC_OPEN_MAX);
+		if (maxfd == -1)
+			maxfd = 8192;
+		for (fd = 0; fd < maxfd; fd++)
+			close(fd);
+
+		usleep(delay);
+		_exit(execvp(cmd[0], cmd));
+	}
+
+	if (pid == -1)
+		return -1;
+
+	if (waitpid(pid, &rc, 0) == -1)
+		return -1;
+
+	if (WIFEXITED(rc)) {
+		errno = WEXITSTATUS(rc);
+		if (errno)
+			rc = -1;
+		else
+			rc = 0;
+	} else if (WIFSIGNALED(rc)) {
+		errno = EINTR;
+		rc = -1;
+	} else
+		rc = -1;
+
+	return rc;
+}

test/.gitignore

@@ -15,6 +15,7 @@
 /printhdr
 /progress
 /rsync
+/runbg
 /str
 /strmatch
 /systemf

test/Makefile.am

@@ -30,6 +30,7 @@ TESTS          += pidfile
 TESTS          += printhdr
 TESTS          += progress
 TESTS          += rsync
+TESTS          += runbg
 TESTS          += str
 TESTS          += strmatch
 TESTS          += systemf

test/runbg.c

@@ -0,0 +1,23 @@
+#include "check.h"
+
+#define file "/tmp/runbg.txt"
+
+int main(void)
+{
+	char *cmd[] = {
+		"sh", "-c", "echo 'hello world' > " file, NULL
+	};
+
+	erase(file);
+	test(runbg(cmd, 100000), "Calling runbg");
+
+	if (test(fexist(file), "Verifying %s does not yet exist", file))
+		return 1;
+
+	test(sleep(1), "Waiting for runbg");
+
+	if (test(!fexist(file), "Verifying %s has been created", file))
+		return 1;
+
+	return 0;
+}