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Paweł
a22a5fae7c
Attribute substitution only looked at the device's own sysfs directory,
while the matching key ATTRS{} walks parents. Devices without an
attribute of their own, partitions in particular whose serial lives in
the parent disk, therefore substituted to an empty string.
167 lines
3.8 KiB
C
167 lines
3.8 KiB
C
/* sysfs attribute reader and parent-chain walker
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*
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* Copyright (c) 2025 Joachim Wiberg <troglobit@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#ifdef _LIBITE_LITE
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# include <libite/lite.h>
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#else
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# include <lite/lite.h>
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#endif
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#include "sysfs.h"
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int sysfs_read_file(const char *path, char *buf, size_t len)
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{
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FILE *fp;
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fp = fopen(path, "r");
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if (!fp)
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return -1;
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if (!fgets(buf, len, fp)) {
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fclose(fp);
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return -1;
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}
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fclose(fp);
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chomp(buf);
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return 0;
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}
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int sysfs_read_attr(const char *devpath, const char *attr,
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char *buf, size_t len)
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{
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char path[PATH_MAX];
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snprintf(path, sizeof(path), "/sys%s/%s", devpath, attr);
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return sysfs_read_file(path, buf, len);
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}
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struct attr_ctx {
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const char *attr;
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char *buf;
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size_t len;
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};
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static int attr_cb(const char *syspath, void *data)
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{
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struct attr_ctx *ctx = data;
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char path[PATH_MAX];
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snprintf(path, sizeof(path), "%s/%s", syspath, ctx->attr);
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if (sysfs_read_file(path, ctx->buf, ctx->len) == 0)
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return 0; /* found, stop walking */
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return 1;
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}
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int sysfs_read_attr_chain(const char *devpath, const char *attr,
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char *buf, size_t len)
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{
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struct attr_ctx ctx = { attr, buf, len };
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if (!devpath || !attr || !*attr)
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return -1;
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/* Device itself first then walk up toward the parent devices */
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if (sysfs_read_attr(devpath, attr, buf, len) == 0)
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return 0;
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sysfs_parent_walk(devpath, attr_cb, &ctx);
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return buf[0] ? 0 : -1;
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}
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int sysfs_parent_walk(const char *devpath,
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int (*cb)(const char *syspath, void *data),
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void *data)
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{
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char syspath[PATH_MAX];
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char *p;
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snprintf(syspath, sizeof(syspath), "/sys%s", devpath);
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while (1) {
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if (cb(syspath, data) == 0)
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return 0;
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/* Strip last path component */
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p = strrchr(syspath, '/');
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if (!p || p == syspath)
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break;
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*p = 0;
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/* Do not walk above /sys/devices */
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if (!strcmp(syspath, "/sys/devices") ||
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!strcmp(syspath, "/sys"))
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break;
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}
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return -1;
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}
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int sysfs_read_subsystem(const char *syspath, char *buf, size_t len)
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{
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char lpath[PATH_MAX], target[PATH_MAX];
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const char *p;
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ssize_t n;
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snprintf(lpath, sizeof(lpath), "%s/subsystem", syspath);
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n = readlink(lpath, target, sizeof(target) - 1);
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if (n < 0)
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return -1;
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target[n] = 0;
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p = strrchr(target, '/');
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snprintf(buf, len, "%s", p ? p + 1 : target);
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return 0;
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}
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int sysfs_read_driver(const char *syspath, char *buf, size_t len)
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{
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char lpath[PATH_MAX], target[PATH_MAX];
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const char *p;
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ssize_t n;
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snprintf(lpath, sizeof(lpath), "%s/driver", syspath);
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n = readlink(lpath, target, sizeof(target) - 1);
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if (n < 0)
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return -1;
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target[n] = 0;
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p = strrchr(target, '/');
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snprintf(buf, len, "%s", p ? p + 1 : target);
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return 0;
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}
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/**
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* Local Variables:
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* indent-tabs-mode: t
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* c-file-style: "linux"
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* End:
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*/
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