utils-std

commit: 722a1008ed5cf8ecb3396d59e57e3c437e4f6a77
parent 229f34110452281f787f1d3ca31c90247bcea57c
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Fri,  1 Mar 2024 06:32:33 +0100

cmd/df: escape getmntent output, note on musl prior to 1.2.5

Diffstat:
M
cmd/df.c
61
+++++++++++++++++++++----------------------------------------

1 file changed, 21 insertions(+), 40 deletions(-)
diff --git a/cmd/df.c b/cmd/df.c
@@ -7,6 +7,7 @@
 
 #include "../lib/humanize.h"
 
+#include <ctype.h> // iscntrl, isspace
 #include <errno.h> // errno
 #include <mntent.h>
 #include <stdbool.h>
@@ -18,28 +19,12 @@
 
 size_t forced_bsize = 0;
 
+// Replaces control characters and whitespaces with '?' in-place (no allocation)
 static void
-unescape_path(char *path)
+static_escape(char *str)
 {
-	char *needle   = "\\040";
-	size_t esc_len = 3; // 4 chars but leading-slash is kept for space
-
-	char *str = strstr(path, needle);
-
-	if(str != NULL)
-	{
-		size_t pos = 0;
-
-		str[pos++] = ' ';
-
-		while(str[pos] != '\0')
-		{
-			str[pos] = str[pos + esc_len];
-			pos++;
-		}
-
-		unescape_path(str + pos);
-	}
+	for(int i = 0; i < strlen(str); i++)
+		if(iscntrl(str[i]) || isspace(str[i])) str[i] = '?';
 }
 
 int
@@ -84,8 +69,8 @@ main(int argc, char *argv[])
 		printf("Filesystem Total Used Available Use%% Mountpoint\n");
 	}
 
-	FILE *mnt = setmntent(MOUNTED, "r");
-	if(mnt == NULL)
+	FILE *mounted = setmntent(MOUNTED, "r");
+	if(mounted == NULL)
 	{
 		fprintf(stderr, "df: Error opening setmntent(\"" MOUNTED "\", \"r\"): %s", strerror(errno));
 		return 1;
@@ -93,31 +78,27 @@ main(int argc, char *argv[])
 
 	while(1)
 	{
-		struct mntent *mntent = getmntent(mnt);
+		struct mntent *mntent = getmntent(mounted);
 		if(mntent == NULL) break;
 
-		// Linux escapes spaces in filesystems and mountpoints with \040
-		// which statvfs(3) doesn't interprets
-		// Also shouldn't be printed out to not break parsing of df(1) output
-		char *mountpoint = strdup(mntent->mnt_dir);
-		if(mountpoint == NULL)
-		{
-			fprintf(stderr, "df: Failed duplicating mnt_dir string: %s\n", strerror(errno));
-			return 1;
-			exit(1);
-		}
-		unescape_path(mountpoint);
-
+		// Note: musl prior to 1.2.5 has broken getmntent when octal sequences and carriage return is used
+		// https://git.musl-libc.org/cgit/musl/commit/src/misc/mntent.c?id=f314e133929b6379eccc632bef32eaebb66a7335
+		// https://git.musl-libc.org/cgit/musl/commit/src/misc/mntent.c?id=ee1d39bc1573c1ae49ee6b658938b56bbef95a6c
 		struct statvfs stats;
-		if(statvfs(mountpoint, &stats) != 0)
+		if(statvfs(mntent->mnt_dir, &stats) != 0)
 		{
-			fprintf(stderr, "df: Error statvfs(\"%s\", _): %s\n", mountpoint, strerror(errno));
+			fprintf(stderr, "df: Error statvfs(\"%s\", _): %s\n", mntent->mnt_dir, strerror(errno));
+
+			static_escape(mntent->mnt_fsname);
+			static_escape(mntent->mnt_dir);
 			printf("%s - - - - %s\n", mntent->mnt_fsname, mntent->mnt_dir);
 
-			free(mountpoint);
 			continue;
 		}
-		free(mountpoint);
+
+		// Needs to be done after calling statvfs(3)
+		static_escape(mntent->mnt_fsname);
+		static_escape(mntent->mnt_dir);
 
 		size_t percent = 0;
 		size_t total   = stats.f_frsize * stats.f_blocks;
@@ -166,7 +147,7 @@ main(int argc, char *argv[])
 		}
 	}
 
-	endmntent(mnt);
+	endmntent(mounted);
 
 	return 0;
 }