c881c733b — BusyBox

Subject

cleanup comments and coding style and rewrite the mdev.conf parser to use common busybox functions and call strdup() less often ... saves a ~few hundred bytes

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

util-linux/mdev.c +98 -95

util-linux/mdev.c+98 -95

@@ -35,154 +35,146 @@ static void make_device(char *path, int delete)
	/* Try to read major/minor string. Note that the kernel puts \n after
	* the data, so we don't need to worry about null terminating the string
	* because sscanf() will stop at the first nondigit, which \n is. We
-	* also depend on path having writeable space after it. */
-
+	* also depend on path having writeable space after it.
+	*/
	if (!delete) {
	strcat(path, "/dev");
	len = open_read_close(path, temp + 1, 64);
	*temp++ = 0;
-	if (len < 1) return;
+	if (len < 1)
+	return;
	}

	/* Determine device name, type, major and minor */
-
	device_name = bb_basename(path);
-	type = path[5]=='c' ? S_IFCHR : S_IFBLK;
-
-	/* If we have a config file, look up permissions for this device */
+	type = (path[5] == 'c' ? S_IFCHR : S_IFBLK);

	if (ENABLE_FEATURE_MDEV_CONF) {
-	char conf, pos, *end;
-	int line, fd;
+	FILE *fp;
+	char line, vline;
+	size_t lineno = 0;

-	/* mmap the config file */
-	fd = open("/etc/mdev.conf", O_RDONLY);
-	if (fd < 0)
-	goto end_parse;
-	len = xlseek(fd, 0, SEEK_END);
-	conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
-	close(fd);
-	if (!conf)
+	/* If we have a config file, look up the user settings */
+	fp = fopen_or_warn("/etc/mdev.conf", "r");
+	if (!fp)
	goto end_parse;

-	line = 0;
-	/* Loop through lines in mmaped file*/
-	for (pos=conf; pos-conf<len;) {
+	while ((vline = line = xmalloc_getline(fp)) != NULL) {
	int field;
-	char *end2;

-	line++;
-	/* find end of this line */
-	for (end=pos; end-conf<len && *end!='\n'; end++)
-	;
+	/* A pristine copy for command execution. */
+	char *orig_line;
+	if (ENABLE_FEATURE_MDEV_EXEC)
+	orig_line = xstrdup(line);
+
+	++lineno;

	/* Three fields: regex, uid:gid, mode */
-	for (field=0; field < (3 + ENABLE_FEATURE_MDEV_EXEC);
-	field++)
-	{
-	/* Skip whitespace */
-	while (pos<end && isspace(*pos)) pos++;
-	if (pos==end \|\| *pos=='#') break;
-	for (end2=pos;
-	end2<end && !isspace(end2) && end2!='#'; end2++)
-	;
+	for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_EXEC); ++field) {
+
+	/* Find a non-empty field */
+	char *val;
+	do {
+	val = strtok(vline, " \t");
+	vline = NULL;
+	} while (val && !*val);
+	if (!val)
+	break;

	if (field == 0) {
-	/* Regex to match this device */

-	char *regex = xstrndup(pos, end2-pos);
+	/* Regex to match this device */
	regex_t match;
	regmatch_t off;
	int result;

	/* Is this it? */
-	xregcomp(&match,regex, REG_EXTENDED);
+	xregcomp(&match, val, REG_EXTENDED);
	result = regexec(&match, device_name, 1, &off, 0);
	regfree(&match);
-	free(regex);

	/* If not this device, skip rest of line */
-	if (result \|\| off.rm_so
-	\|\| off.rm_eo != strlen(device_name))
-	break;
-	}
-	if (field == 1) {
-	/* uid:gid */
+	if (result \|\| off.rm_so \|\| off.rm_eo != strlen(device_name))
+	goto next_line;

-	char s, s2;
+	} else if (field == 1) {

-	/* Find : */
-	for (s=pos; s<end2 && *s!=':'; s++)
-	;
-	if (s == end2) break;
+	/* uid:gid device ownership */
+	struct passwd *pass;
+	struct group *grp;
+
+	char *str_uid = val;
+	char *str_gid = strchr(val, ':');
+	if (str_gid)
+	*str_gid = '\0', ++str_gid;

	/* Parse UID */
-	uid = strtoul(pos, &s2, 10);
-	if (s != s2) {
-	struct passwd *pass;
-	char *_unam = xstrndup(pos, s-pos);
-	pass = getpwnam(_unam);
-	free(_unam);
-	if (!pass) break;
+	pass = getpwnam(str_uid);
+	if (pass)
	uid = pass->pw_uid;
-	}
-	s++;
+	else
+	uid = strtoul(str_uid, NULL, 10);
+
	/* parse GID */
-	gid = strtoul(s, &s2, 10);
-	if (end2 != s2) {
-	struct group *grp;
-	char *_grnam = xstrndup(s, end2-s);
-	grp = getgrnam(_grnam);
-	free(_grnam);
-	if (!grp) break;
+	grp = getgrnam(str_gid);
+	if (grp)
	gid = grp->gr_gid;
-	}
-	}
-	if (field == 2) {
-	/* mode */
+	else
+	gid = strtoul(str_gid, NULL, 10);

-	mode = strtoul(pos, &pos, 8);
-	if (pos != end2) break;
-	}
-	if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
-	// Command to run
+	} else if (field == 2) {
+
+	/* Mode device permissions */
+	mode = strtoul(val, NULL, 8);
+
+	} else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
+
+	/* Optional command to run */
	const char s = "@$";
-	const char *s2;
-	s2 = strchr(s, *pos++);
+	const char s2 = strchr(s, val);
+
	if (!s2) {
-	// Force error
+	/* Force error */
	field = 1;
	break;
	}
-	if ((s2-s+1) & (1<<delete))
-	command = xstrndup(pos, end-pos);
-	}

-	pos = end2;
+	/* Correlate the position in the "@$*" with the delete
+	* step so that we get the proper behavior.
+	*/
+	if ((s2 - s + 1) & (1 << delete))
+	command = xstrdup(orig_line + (val + 1 - line));
+	}
	}

	/* Did everything parse happily? */
+	if (field <= 2)
+	bb_error_msg_and_die("bad line %i", lineno);

-	if (field > 2) break;
-	if (field) bb_error_msg_and_die("bad line %d",line);
-
-	/* Next line */
-	pos = ++end;
+	next_line:
+	free(line);
+	if (ENABLE_FEATURE_MDEV_EXEC)
+	free(orig_line);
	}
-	munmap(conf, len);
+
+	if (ENABLE_FEATURE_CLEAN_UP)
+	fclose(fp);
+
	end_parse: /* nothing */ ;
	}

	umask(0);
	if (!delete) {
-	if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
+	if (sscanf(temp, "%d:%d", &major, &minor) != 2)
+	return;
	if (mknod(device_name, mode \| type, makedev(major, minor)) && errno != EEXIST)
	bb_perror_msg_and_die("mknod %s", device_name);

	if (major == root_major && minor == root_minor)
	symlink(device_name, "root");

-	if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
+	if (ENABLE_FEATURE_MDEV_CONF)
+	chown(device_name, uid, gid);
	}
	if (command) {
	/* setenv will leak memory, so use putenv */
@@ -195,7 +187,8 @@ static void make_device(char *path, int delete)
	free(s);
	free(command);
	}
-	if (delete) unlink(device_name);
+	if (delete)
+	remove_file(device_name, FILEUTILS_FORCE);
	}

	/* File callback for /sys/ traversal */
@@ -296,9 +289,12 @@ int mdev_main(int argc, char **argv)

	xchdir("/dev");

-	/* Scan */
-
	if (argc == 2 && !strcmp(argv[1],"-s")) {
+
+	/* Scan:
+	* mdev -s
+	*/
+
	struct stat st;

	xstat("/", &st);
@@ -313,9 +309,14 @@ int mdev_main(int argc, char **argv)
	ACTION_RECURSE \| ACTION_FOLLOWLINKS,
	fileAction, dirAction, temp, 0);

-	/* Hotplug */
-
	} else {
+
+	/* Hotplug:
+	* env ACTION=... DEVPATH=... mdev
+	* ACTION can be "add" or "remove"
+	* DEVPATH is like "/block/sda" or "/class/input/mice"
+	*/
+
	action = getenv("ACTION");
	env_path = getenv("DEVPATH");
	if (!action \|\| !env_path)
@@ -332,6 +333,8 @@ int mdev_main(int argc, char **argv)
	}
	}

-	if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
+	if (ENABLE_FEATURE_CLEAN_UP)
+	RELEASE_CONFIG_BUFFER(temp);
+
	return 0;
	}