Bump version for v1.9.3 release

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

.gitignore

@@ -22,3 +22,4 @@ aclocal.m4
 ar-lib
 autom4te.cache
 libite*
+test-driver

ChangeLog.md

@@ -4,6 +4,50 @@ Change Log
 All notable changes to the project are documented in this file.
 
 
+[v1.9.3][] - 2017-10-24
+-----------------------
+
+### Changes
+- `initscr()`, use stdout, not stderr, like the rest of the
+  `conio.h` macros.  Also, stderr may be redirected by user
+- `tree()`, update unit test, use standard directries
+
+### Fixes
+- `initscr()`, verify that both stdin and stdout are real TTYs
+  before messing up output or blocking on input for the user
+- `tree()`, increase internal buffer slightly, output may be
+  truncated otherwise.  Found by GCC 7.2
+
+
+[v1.9.2][] - 2017-07-09
+-----------------------
+
+### Changes
+- Add `initscr()` function to query screen size
+- Convert `printheader()` to a static inline function
+
+
+[v1.9.1][] - 2017-07-03
+-----------------------
+
+### Changes
+- Add missing `whichp()` predicate function to accompany `which()`
+- Allow `which("ps aux")`, which skips any arguments to command
+
+
+[v1.9.0][] - 2017-07-02
+-----------------------
+
+### Changes
+- Add `which()`, a C implementation of UNIX which(1)
+- Add `printheader()`, prints a top-like table heading for client tools
+- Remove `UNUSED()` macro, recommended to disable GCC warning instead
+
+### Fixes
+- Fix issue #6: `touch()` does not update mtime if file exists
+- Fix non-writable `tempfile()`, now with proper unit test
+
+
 [v1.8.3][] - 2017-01-08
 -----------------------
 
@@ -231,7 +275,10 @@ problems this may cause!
 Initial extraction of frog DNA from [Finit][].  See [README][] for API details.
 
 
-[UNRELEASED]: https://github.com/troglobit/libite/compare/v1.8.3...HEAD
+[UNRELEASED]: https://github.com/troglobit/libite/compare/v1.9.2...HEAD
+[v1.9.2]: https://github.com/troglobit/libite/compare/v1.9.1...v1.9.2
+[v1.9.1]: https://github.com/troglobit/libite/compare/v1.9.0...v1.9.1
+[v1.9.0]: https://github.com/troglobit/libite/compare/v1.8.3...v1.9.0
 [v1.8.3]: https://github.com/troglobit/libite/compare/v1.8.2...v1.8.3
 [v1.8.2]: https://github.com/troglobit/libite/compare/v1.8.1...v1.8.2
 [v1.8.1]: https://github.com/troglobit/libite/compare/v1.8.0...v1.8.1

HACKING.md

@@ -4,9 +4,10 @@ Maintenance and Release Checklist
 Maintenance
 -----------
 
+* Encourage contributors to write tests, in particular for new features
+* Run tests regularly, use Travis-CI to do this automatically
 * Leverage GitHub issues for milestone planning
 * Reference issues from GitHub pull requests to alert issue subscribers
-* Encourage contributors to write unit tests
 * Bump library ABI version just before release!
 
 
@@ -17,6 +18,7 @@ Release Checklist
   - Inform users in a plain language of changes and bug fixes
   - Do *not* copy-paste GIT commit logs!
   - Order entrys according to importance, most relevant first
+* Run unit tests: `make check`
 * Do we need to bump the ABI version? (Probably, see below)
 * Tag
 * Push last commit(s) *and* tags to GitHub
@@ -25,7 +27,7 @@ Release Checklist
         make distclean
         ./autogen.sh
         ./configure
-		make release
+        make release
 
 * Create new release in GitHub releases page
 * Copy and paste ChangeLog entry, check any stale links!
@@ -54,14 +56,31 @@ It must be updated according to the [GNU Libtool recommendations][1]:
    release of your software.  More frequent updates are unnecessary, and
    only guarantee that the current interface number gets larger faster.
 3. If the library *source code has changed at all* since the last update,
-   then increment revision (`c:r:a` --> `c:r+1:a`)
-4. If any *interfaces have been added, removed, or changed* since last
-   update, increment current, and zero revision (`c:r:a` --> `c+1:0:0`)
+   then increment revision (`c:r:a` becomes `c:r+1:a`).
+4. If any *interfaces have been added, removed, or changed* since the
+   last update, increment current, and set revision to 0.
 5. If any *interfaces have been added* since the last public release,
    then increment age.
 6. If any *interfaces have been removed or changed* since the last
    public release, then set age to 0.
 
+The libtool ABI versioning logic is very confusing but works if you just
+disable your brain and follow the rules, one by one.
+
+**Example #1:** a new function has been added, none of the existing ones
+have changed.  The initial version is 1:0:0, we follow the rules above to
+the letter: increase revision, increase current and set revision to zero,
+and finally increase age.  This, rather confusingly, gives us 2:0:1 which
+libtool then translates to `libconfuse.so.1.1.0`.
+
+**Example #2:** some existing functions are changed, they now return an
+`int` instead of `void`.  The initial version is 0:0:0, and we follow the
+rules again: increment revision, increment current and set revision to
+zero, set age to zero.  This gives us 1:0:0, which is then translated to
+ `libconfuse.so.1.0.0`.
+
+### Note
+
 Usually, non-developers have no interest in running development versions
 (releases are frequent enough), and developers are expected to know how
 to juggle versions.  In such an ideal world, it is good enough to bump

Makefile.am

@@ -6,11 +6,11 @@ pkginclude_HEADERS  = lite.h queue.h conio.h tree.h strlite.h strdupa.h strndupa
 libite_la_SOURCES   = chomp.c copyfile.c dir.c fexist.c fisdir.c fmode.c fparseln.c		\
 		      fsendfile.c ifconfig.c lfile.c makepath.c pidfile.c pidfilefn.c		\
 		      progress.c reallocarray.c rsync.c strlcpy.c strlcat.c strtonum.c		\
-		      tempfile.c tree.c
+		      tempfile.c tree.c which.c
 
 libite_la_CPPFLAGS  = -D_GNU_SOURCE
 libite_la_CFLAGS    = -W -Wall -Wextra
-libite_la_LDFLAGS   = $(AM_LDFLAGS) -version-info 3:1:0
+libite_la_LDFLAGS   = $(AM_LDFLAGS) -version-info 4:1:0
 
 pkgconfigdir        = $(libdir)/pkgconfig
 pkgconfig_DATA      = libite.pc
@@ -18,6 +18,10 @@ doc_DATA            = README.md LICENSE
 EXTRA_DIST          = README.md LICENSE ChangeLog.md
 SUBDIRS             = tests
 
+## Generate .deb package
+package:
+	@dpkg-buildpackage -uc -us -B
+
 ## Generate MD5 checksum file
 MD5 = md5sum
 md5-dist:

README.md

@@ -143,10 +143,6 @@ Helper Macros
   Returns the number of elements in an array.  From the great book, The
   Practice of Programming, by Kernighan and Pike.
 
-- `UNUSED(var)`
-
-  Shorter and more readable version of `var __attribute__ ((unused))`
-
 
 Generic Functions
 -----------------
@@ -292,6 +288,16 @@ Generic Functions
   optional listing of file and directory permissions if `show_perms` is
   set.  The `path` argument should be a directory.
 
+- `which(cmd)`, `whichp(cmd)`
+
+  C implementation of UNIX which(1).  Returns a malloc'ed string with the
+  full path to `cmd` on success, otherwise `NULL`.
+  
+  `whichp()` is a predicate function, returns `TRUE` or `FALSE`.
+
+  **Note:** `which("/bin/ps aux")` will return `/bin/ps`, or `TRUE`,
+  provided of course `/bin/ps` exists.
+
 
 GNU Functions
 -------------

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT(libite, 1.8.3, https://github.com/troglobit/libite/issues)
+AC_INIT(libite, 1.9.3, https://github.com/troglobit/libite/issues)
 AM_INIT_AUTOMAKE([1.11 foreign no-dist-gzip dist-xz])
 AM_SILENT_RULES([yes])
 

conio.h

@@ -1,6 +1,6 @@
 /* A conio.h like implementation for VTANSI displays.
  *
- * Copyright (c) 2009-2013  Joachim Nilsson <troglobit@gmail.com>
+ * Copyright (c) 2009-2017  Joachim Nilsson <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
@@ -19,6 +19,8 @@
 #define CONIO_H_
 
 #include <stdio.h>
+#include <termios.h>
+#include <unistd.h>
 
 /* Attributes */
 #define RESETATTR    0
@@ -48,29 +50,98 @@
 #define LIGHTCYAN    0x16
 #define WHITE        0x17
 
-/* Esc[2JEsc[1;1H             - Clear screen and move cursor to 1,1 (upper left) pos. */
-#define clrscr()              fputs ("\033[2J\033[1;1H", stdout)
-/* Esc[K                      - Erases from the current cursor position to the end of the current line. */
-#define clreol()              fputs ("\033[K", stdout)
-/* Esc[2K                     - Erases the entire current line. */
-#define delline()             fputs ("\033[2K", stdout)
-/* Esc[Line;ColumnH           - Moves the cursor to the specified position (coordinates) */
-#define gotoxy(x,y)           printf("\033[%d;%dH", y, x)
-/* Esc[?25l (lower case L)    - Hide Cursor */
-#define hidecursor()          fputs ("\033[?25l", stdout)
-/* Esc[?25h (lower case H)    - Show Cursor */
-#define showcursor()          fputs ("\033[?25h", stdout)
+#ifndef SCREEN_WIDTH
+#define SCREEN_WIDTH 80		/* Override using, e.g. #define SCREEN_WIDTH tty_width() */
+#endif
 
-/* Esc[Value;...;Valuem       - Set Graphics Mode */
-#define __set_gm(attr,color,val)					\
-	if (!color)							\
-		printf("\033[%dm", attr);					\
+/* Esc[2JEsc[1;1H             - Clear screen and move cursor to 1,1 (upper left) pos. */
+#define clrscr()              fputs("\033[2J\033[1;1H", stdout)
+/* Esc[K                      - Erases from the current cursor position to the end of the current line. */
+#define clreol()              fputs("\033[K", stdout)
+/* Esc[2K                     - Erases the entire current line. */
+#define delline()             fputs("\033[2K", stdout)
+/* Esc[Line;ColumnH           - Moves the cursor to the specified position (coordinates) */
+#define gotoxy(x,y)           fprintf(stdout, "\033[%d;%dH", y, x)
+/* Esc[?25l (lower case L)    - Hide Cursor */
+#define hidecursor()          fputs("\033[?25l", stdout)
+/* Esc[?25h (lower case H)    - Show Cursor */
+#define showcursor()          fputs("\033[?25h", stdout)
+
+/* Esc[Value;...;Valuem       - Set Graphics Mode (attr, color, val) */
+#define __set_gm(a,c,v)							\
+	if (!c)								\
+		fprintf(stdout, "\033[%dm", a);				\
 	else								\
-		printf("\033[%d;%dm", color & 0x10 ? 1 : 0, (color & 0xF) + val)
+		fprintf(stdout, "\033[%d;%dm", c & 0x10 ? 1 : 0, (c & 0xF) + v)
 #define textattr(attr)        __set_gm(attr, 0, 0)
 #define textcolor(color)      __set_gm(RESETATTR, color, 30)
 #define textbackground(color) __set_gm(RESETATTR, color, 40)
 
+/* Print table heading @line to @fp, with optional leading newline */
+static inline void printheader(FILE *fp, const char *line, int nl)
+{
+	fprintf(fp ?: stdout,
+		"%s\033[7m%s%*s\033[0m\n",
+		nl ? "\n" : "",
+		line, SCREEN_WIDTH - (int)strlen(line), "");
+}
+
+/* Requries: #inlude <termios.h> and #include <poll.h> */
+static inline void initscr(int *row, int *col)
+{
+	if (!row || !col)
+		return;
+
+#if defined(TCSANOW) && defined(POLLIN)
+	struct termios tc, saved;
+	struct pollfd fd = { STDIN_FILENO, POLLIN, 0 };
+
+	if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO)) {
+		*row = 24;
+		*col = 80;
+		return;
+	}
+
+	/* Disable echo to terminal while probing */
+	tcgetattr(STDOUT_FILENO, &tc);
+	saved = tc;
+	tc.c_cflag |= (CLOCAL | CREAD);
+	tc.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
+	tcsetattr(STDOUT_FILENO, TCSANOW, &tc);
+
+	/*
+	 * Save cursor pos+attr
+	 * Diable top+bottom margins
+	 * Set cursor at the far bottom,right pos
+	 * Query term for resulting pos
+	 */
+	fprintf(stdout, "\e7" "\e[r" "\e[999;999H" "\e[6n");
+	fflush(stdout);
+
+	/*
+	 * Wait here for terminal to echo back \e[row,lineR ...
+	 */
+	if (poll(&fd, 1, 300) <= 0 || scanf("\e[%d;%dR", row, col) != 2) {
+		*row = 24;
+		*col = 80;
+	}
+
+	/*
+	 * Restore above saved cursor pos+attr
+	 */
+	fprintf(stdout, "\e8");
+	fflush(stdout);
+
+	/* Restore terminal */
+	tcsetattr(STDOUT_FILENO, TCSANOW, &saved);
+
+	return;
+#else
+	*row = 24;
+	*col = 80;
+#endif
+}
+
 #endif /* CONIO_H_ */
 
 /**

debian/changelog

@@ -1,3 +1,33 @@
+libite (1.9.3-1) unstable; urgency=low
+
+  * New upstream release, v1.9.3, fixes to conio.h, initscr() and tree().
+
+ -- Joachim Nilsson <troglobit@gmail.com>  Tue, 24 Oct 2017 08:49:54 +0200
+
+libite (1.9.2-1) unstable; urgency=low
+
+  * New upstream reelase, v1.9.2, see upstream ChangeLog for details.
+
+ -- Joachim Nilsson <troglobit@gmail.com>  Tue, 15 Aug 2017 08:15:14 +0200
+
+libite (1.9.1-1) unstable; urgency=low
+
+  * New upstream reelase, v1.9.1.
+
+ -- Joachim Nilsson <troglobit@gmail.com>  Sun, 02 Jul 2017 19:23:00 +0100
+
+libite (1.9.0-1) unstable; urgency=low
+
+  * New upstream reelase.
+
+ -- Joachim Nilsson <troglobit@gmail.com>  Sun, 02 Jul 2017 19:23:00 +0100
+
+libite (1.8.3-1) unstable; urgency=low
+
+  * New upstream reelase.
+
+ -- Joachim Nilsson <troglobit@gmail.com>  Sun, 08 Jan 2017 15:22:26 +0100
+
 libite (1.8.2-1) unstable; urgency=low
 
   * Initial release.

lite.h

@@ -85,11 +85,19 @@ int     tree(char *path, int show_perms);
 void    progress       (int percent, int max_width);
 void    progress_simple(int percent);
 
+char   *which      (const char *cmd);
+int     whichp     (const char *cmd);
+
 #ifndef touch
+#include <sys/stat.h>		/* utimensat() */
+#include <sys/time.h>		/* utimensat() on *BSD */
 static inline int touch(const char *path)
 {
-	if (mknod((path), S_IFREG|0644, 0) && errno != EEXIST)
+	if (mknod((path), S_IFREG|0644, 0)) {
+		if (errno == EEXIST)
+			return utimensat(0, path, NULL, 0);
 		return -1;
+	}
 	return 0;
 }
 #endif
@@ -151,11 +159,6 @@ static inline int erase(const char *path)
 #define NELEMS(array) (sizeof(array) / sizeof(array[0]))
 #endif
 
-/* Mark a function variable as unused, useful for generic callbacks */
-#ifndef UNUSED
-#define UNUSED(x) UNUSED_ ## x __attribute__ ((unused))
-#endif
-
 /* Does directory end with a slash? */
 static inline int fisslashdir(char *dir)
 {
@@ -169,9 +172,9 @@ static inline int fisslashdir(char *dir)
 }
 
 /* Compat */
-#define copy_filep(src,dst)        fcopyfile(src,dst)
-#define pidfile_read_pid(file)     pifile_read(file)
-#define signal_pidfile(file,signo) pidfile_signal(file,signo)
+#define copy_filep(src, dst)        fcopyfile(src, dst)
+#define pidfile_read_pid(file)      pifile_read(file)
+#define signal_pidfile(file, signo) pidfile_signal(file, signo)
 
 #endif /* LITE_H_ */
 

tempfile.c

@@ -45,7 +45,7 @@ FILE *tempfile(void)
 	if (-1 == fd)
 		return NULL;
 
-	return fdopen(fd, "rw");
+	return fdopen(fd, "w+");
 #else
 	return tmpfile(); /* Fallback on older GLIBC/Linux and actual UNIX systems */
 #endif

tests/.gitignore

@@ -12,4 +12,6 @@ pidfile
 progress
 rsync
 tempfile
+touch
 tree
+which

tests/Makefile.am

@@ -11,14 +11,17 @@ TESTS          += fsendfile
 TESTS          += lfile
 TESTS          += makepath
 TESTS          += pidfile
+TESTS          += touch
 TESTS          += progress
 TESTS          += rsync
 TESTS          += tempfile
 TESTS          += tree
+TESTS          += which
 
 check_PROGRAMS  = $(TESTS)
 
 # Ignore warnings about unused result, in e.g. write()
-CPPFLAGS        = -D_GNU_SOURCE
+CFLAGS         += -Wno-unused-result
+CPPFLAGS       += -D_GNU_SOURCE
 LDADD           = -L../ ../libite.la
-LDFLAGS         = -static
+LDFLAGS        += -static

tests/check.h

@@ -6,8 +6,11 @@
 #include <string.h>
 #include <time.h>
 
+#include "../conio.h"
 #include "../lite.h"
 
+#define PRINT(args...) if (verbose) printf(args)
+
 #define fail_unless(test)						\
   do {									\
     if (!(test)) {							\

tests/lfile.c

@@ -6,7 +6,7 @@
 static int fstab(void)
 {
 	int field = 1;
-	char *token, *dev;
+	char *token;
 	lfile_t *lf;
 
 	lf = lfopen(FSTAB, " \t\n");
@@ -15,12 +15,19 @@ static int fstab(void)
 		return 1;
 	}
 
+	printheader(NULL, "FILE SYSTEM                               MOUNT     OPTIONS            D P", 0);
 	while ((token = lftok(lf))) {
 		if (field == 1)
-			dev = token;
+			printf("%-41s ", token);
+		if (field == 2)
+			printf("%-9s ", token);
+		if (field == 4)
+			printf("%-17s  ", token);
+		if (field == 5)
+			printf("%d ", atoi(token));
 		if (field == 6) {
 			field = 0;
-			printf("Found %s passno %d\n", dev, atoi(token));
+			printf("%d\n", atoi(token));
 		}
 
 		field++;

tests/pidfile.c

@@ -6,8 +6,6 @@
 
 #include "check.h"
 
-#define PRINT(args...) if (verbose) printf(args)
-
 extern char *__pidfile_name;
 extern char *__pidfile_path;
 
@@ -17,13 +15,13 @@ static char PIDFILE[42];
 static int verbose = 0;
 static struct stat before, after;
 
-static void sigterm_handler(int UNUSED(signo))
+static void sigterm_handler(int signo)
 {
 	PRINT("Exiting ...\n");
 	remove(PIDFILE);
 }
 
-static void sigalrm_handler(int UNUSED(signo))
+static void sigalrm_handler(int signo)
 {
 	PRINT("Calling pidfile(%s)\n", pidfile_arg ?: "NULL");
 	if (pidfile(pidfile_arg))

tests/tempfile.c

@@ -8,18 +8,29 @@
 #warning O_TMPFILE is missing, either too old GLIBC, Linux, or non-Linux system
 #endif
 
+#define READBACK "Reality is frequently inaccurate.\n"
+
+
 int main(void)
 {
+	int ret;
 	FILE *fp;
+	char buf[80] = "";
 
 	printf("Before tempfile():\n");
-	system("ls -lrt " _PATH_TMP " | tail -3");
+	ret = system("ls -lrt " _PATH_TMP " | tail -3");
 
 	fp = tempfile();
 	fail_unless(fp != NULL);
 
+	ret = fputs(READBACK, fp);
+	rewind(fp);
+	if (fgets(buf, sizeof(buf), fp))
+		fprintf(stderr, "\nRead-back from tempfile: %s", buf);
+	fail_unless(!strcmp(buf, READBACK));
+
 	printf("\nAfter tempfile(), should be same list:\n");
-	system("ls -lrt " _PATH_TMP " | tail -3");
+	ret = system("ls -lrt " _PATH_TMP " | tail -3");
 
 	return fclose(fp);
 }

tests/touch.c

@@ -0,0 +1,61 @@
+#include <err.h>
+#include <paths.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <time.h>
+
+#include "check.h"
+
+int verbose = 0;
+
+
+static int mtime(char *file)
+{
+	int ret;
+	char buf[80];
+	struct stat before, after;
+
+	PRINT("Calling touch() to create file ...\n");
+	touch(file);
+	stat(file, &before);
+
+	/* Must sleep a while here otherwise we execute too fast => no mtime change :-( */
+	usleep(10000);
+
+	PRINT("Calling touch() again to update mtime ...\n");
+	if (touch(file)) {
+		erase(file);
+		err(1, "Failed creating %s", file);
+	}
+	stat(file, &after);
+
+	ret = timespec_newer(&after.st_mtim, &before.st_mtim);
+	PRINT("Before: %s\n", timespec2str(&before.st_mtim, buf, sizeof(buf)));
+	PRINT("After : %s\n", timespec2str(&after.st_mtim, buf, sizeof(buf)));
+
+	return !ret;
+}
+
+int main(int argc, char *argv[])
+{
+	int fd;
+	char file[42] = "/tmp/touch_test.XXXXXX";
+
+	if (argc > 1 && !strcmp(argv[1], "-v"))
+		verbose = 1;
+
+	fd = mkstemp(file);
+	if (fd < 0)
+		err(1, "Failed creating tempfile, %s", file);
+	close(fd);
+
+	return mtime(file);
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style:     "linux"
+ *  compile-command:  "make pidfile && ./pidfile -v"
+ * End:
+ */

tests/tree.c

@@ -7,7 +7,7 @@ int main(void)
 	struct { char *path; int fail; } arr[] = {
 		{ "/etc/passwd", -1 },
 		{ "/dev",         0 },
-		{ "/sbin",        0 },
+		{ "/usr/sbin",    0 },
 	};
 
 	for (i = 0; i < NELEMS(arr); i++) {

tests/which.c

@@ -0,0 +1,49 @@
+#include "check.h"
+
+struct tc {
+	char *cmd;
+	int   exp;
+	int   res;
+};
+
+int main(void)
+{
+	int result = 0;
+	size_t i;
+	struct tc test[] = {
+		{ "ls",          1 },
+		{ "free",        1 },
+		{ "modinfo",     1 },
+		{ "useradd",     1 },
+		{ "/bin/which",  1 },
+		{ "/bin/ps aux", 1 },
+		{ "/etc/passwd", 0 },
+		{ NULL, 0 }
+	};
+
+	for (i = 0; test[i].cmd; i++) {
+		char *path;
+
+		path = which(test[i].cmd);
+		if (!path) {
+			test[i].res = 0;
+			fprintf(stderr, "%20s : Not hot dog\n", test[i].cmd);
+		} else {
+			test[i].res = 1;
+			fprintf(stderr, "%20s : hot dog --> %s\n", test[i].cmd, path);
+			free(path);
+		}
+	}
+
+	for (i = 0; test[i].cmd; i++)
+		result += test[i].exp != test[i].res;
+
+	return result;
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

tree.c

@@ -59,56 +59,54 @@ static void get_perms(struct stat *st, char *buf, size_t len)
 
 static int descend(char *path, int show_perms, char *pfx)
 {
-	int result = 0;
+	int i, n, result = 0;
 	struct stat st;
+	struct dirent **namelist = NULL;
 
 	if (-1 == lstat(path, &st))
 		return 1;
 
-	if ((st.st_mode & S_IFMT) == S_IFDIR) {
-		int i, n;
-		struct dirent **namelist = NULL;
+	if ((st.st_mode & S_IFMT) != S_IFDIR) {
+		errno = ENOTDIR;
+		return -1;
+	}
 
-		n = scandir(path, &namelist, filter, alphasort);
-		if (n) {
-			for (i = 0; i < n; i++) {
-				char t = ' ', p[14] = "", s[256] = "";
-				char buf[256];
-				char dir[80];
+	n = scandir(path, &namelist, filter, alphasort);
+	if (n) {
+		for (i = 0; i < n; i++) {
+			char t = ' ', p[14] = "", s[256] = "";
+			char buf[512];
+			char dir[80];
 
-				if (i + 1 == n) {
-					printf("%s `- ", pfx);
-					snprintf(dir, sizeof(dir), "%s     ", pfx);
-				} else {
-					printf("%s|-- ", pfx);
-					snprintf(dir, sizeof(dir), "%s|    ", pfx);
-				}
-
-				snprintf(buf, sizeof(buf), "%s/%s", path, namelist[i]->d_name);
-				if (!lstat(buf, &st)) {
-					if (show_perms)
-						get_perms(&st, p, sizeof(p));
-					if ((st.st_mode & S_IFMT) == S_IFDIR)
-						t = '/';
-					if (S_ISLNK(st.st_mode)) {
-						snprintf(s, sizeof(s), "-> ");
-						if (-1 == readlink(buf, &s[3], sizeof(s) - 3))
-							s[0] = 0;
-					}
-				}
-
-				printf("%s%s%c%s\n", p, namelist[i]->d_name, t, s);
-				if (t == '/')
-					result += descend(buf, show_perms, dir);
-
-				free(namelist[i]);
+			if (i + 1 == n) {
+				printf("%s `- ", pfx);
+				snprintf(dir, sizeof(dir), "%s     ", pfx);
+			} else {
+				printf("%s|-- ", pfx);
+				snprintf(dir, sizeof(dir), "%s|    ", pfx);
 			}
 
-			free(namelist);
+			snprintf(buf, sizeof(buf), "%s/%s", path, namelist[i]->d_name);
+			if (!lstat(buf, &st)) {
+				if (show_perms)
+					get_perms(&st, p, sizeof(p));
+				if ((st.st_mode & S_IFMT) == S_IFDIR)
+					t = '/';
+				if (S_ISLNK(st.st_mode)) {
+					snprintf(s, sizeof(s), "-> ");
+					if (-1 == readlink(buf, &s[3], sizeof(s) - 3))
+						s[0] = 0;
+				}
+			}
+
+			printf("%s%s%c%s\n", p, namelist[i]->d_name, t, s);
+			if (t == '/')
+				result += descend(buf, show_perms, dir);
+
+			free(namelist[i]);
 		}
-	} else {
-		errno = ENOTDIR;
-		result = -1;
+
+		free(namelist);
 	}
 
 	return result;

which.c

@@ -0,0 +1,127 @@
+/* C implementation of UNIX which(1)
+ *
+ * Copyright (c) 2017  Joachim Nilsson <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.
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>		/* snprintf() */
+#include <stdlib.h>		/* realloc(), free() */
+#include <string.h>		/* strtok_r() */
+#include <unistd.h>		/* access() */
+
+/* Strip any arguments in "/path/to/bin --some args", modifies input string */
+static char *strip_args(char *path)
+{
+	size_t i = 0;
+
+	if (!path)
+		return NULL;
+
+	/* Find first whitespace (space/tab/etc.) */
+	while (path[i] && !isspace(path[i]))
+		i++;
+	path[i] = 0;
+
+	return path;
+}
+
+/*
+ * Like which(1), returns a malloc'ed path to cmd on success, or NULL
+ */
+char *which(const char *cmd)
+{
+	size_t pathlen = 0;
+	char *ptr, *tok, *env, *path = NULL;
+
+	if (!cmd) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	if (cmd[0] == '/') {
+		path = strip_args(strdup(cmd));
+		if (!path)
+			return NULL;
+
+		if (!access(path, X_OK))
+			return path;
+
+		if (path)
+			free(path);
+
+		return NULL;
+	}
+
+	ptr = getenv("PATH");
+	if (!ptr)
+		return NULL;
+
+	env = strdup(ptr);
+	if (!env)
+		return NULL;
+
+	tok = strtok_r(env, ":", &ptr);
+	while (tok) {
+		size_t len = strlen(tok) + strlen(cmd) + 2;
+
+		if (pathlen < len) {
+			path = realloc(path, len);
+			if (!path) {
+				free(env);
+				return NULL;
+			}
+			pathlen = len;
+		}
+
+		snprintf(path, pathlen, "%s/%s", tok, cmd);
+		path = strip_args(path);
+		if (!path || !access(path, X_OK)) {
+			free(env);
+			return path;
+		}
+
+		tok = strtok_r(NULL, ":", &ptr);
+	}
+
+	if (path)
+		free(path);
+	free(env);
+
+	return NULL;
+}
+
+/*
+ * Like which(), above, but only answers TRUE(1)/FALSE(0)
+ */
+int whichp(const char *cmd)
+{
+	char *path;
+
+	path = which(cmd);
+	if (path) {
+		free(path);
+		return 1;
+	}
+
+	return 0;
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */