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Message-Id: <20230120000921.76265-1-ebiggers@kernel.org>
Date: Thu, 19 Jan 2023 16:09:21 -0800
From: Eric Biggers <ebiggers@...nel.org>
To: linux-ext4@...r.kernel.org
Subject: [e2fsprogs PATCH] mk_hugefiles: simplify get_partition_start()
From: Eric Biggers <ebiggers@...gle.com>
search_sysfs_block() is causing -Wformat-truncation warnings. These
could be fixed by checking the return value of snprintf(), instead of
doing buggy checks like 'strlen(p_de->d_name) > SYSFS_PATH_LEN -
strlen(path) - 32', which has an integer underflow bug.
However, the only purpose of search_sysfs_block() is to find the sysfs
directory for a block device by device number. That can trivially be
done using /sys/dev/block/$major:$minor. So just do that instead. Also
make get_partition_start() explicitly Linux-only, as it has never worked
anywhere else.
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
misc/mk_hugefiles.c | 131 +++-----------------------------------------
1 file changed, 7 insertions(+), 124 deletions(-)
diff --git a/misc/mk_hugefiles.c b/misc/mk_hugefiles.c
index 0280b41e7..a7266c8a6 100644
--- a/misc/mk_hugefiles.c
+++ b/misc/mk_hugefiles.c
@@ -2,13 +2,8 @@
* mk_hugefiles.c -- create huge files
*/
-#define _XOPEN_SOURCE 600 /* for inclusion of PATH_MAX in Solaris */
-#define _BSD_SOURCE /* for makedev() and major() */
-#define _DEFAULT_SOURCE /* since glibc 2.20 _BSD_SOURCE is deprecated */
-
#include "config.h"
#include <stdio.h>
-#include <stdarg.h>
#include <string.h>
#include <strings.h>
#include <fcntl.h>
@@ -68,141 +63,29 @@ static char *fn_buf;
static char *fn_numbuf;
int zero_hugefile = 1;
-#define SYSFS_PATH_LEN 300
-typedef char sysfs_path_t[SYSFS_PATH_LEN];
-
-#ifndef HAVE_SNPRINTF
-/*
- * We are very careful to avoid needing to worry about buffer
- * overflows, so we don't really need to use snprintf() except as an
- * additional safety check. So if snprintf() is not present, it's
- * safe to fall back to vsprintf(). This provides portability since
- * vsprintf() is guaranteed by C89, while snprintf() is only
- * guaranteed by C99 --- which for example, Microsoft Visual Studio
- * has *still* not bothered to implement. :-/ (Not that I expect
- * mke2fs to be ported to MS Visual Studio any time soon, but
- * libext2fs *does* get built on Microsoft platforms, and we might
- * want to move this into libext2fs some day.)
- */
-static int my_snprintf(char *str, size_t size, const char *format, ...)
-{
- va_list ap;
- int ret;
-
- va_start(ap, format);
- ret = vsprintf(str, format, ap);
- va_end(ap);
- return ret;
-}
-
-#define snprintf my_snprintf
-#endif
-
-/*
- * Fall back to Linux's definitions of makedev and major are needed.
- * The search_sysfs_block() function is highly unlikely to work on
- * non-Linux systems anyway.
- */
-#ifndef makedev
-#define makedev(maj, min) (((maj) << 8) + (min))
-#endif
-
-static char *search_sysfs_block(dev_t devno, sysfs_path_t ret_path)
-{
- struct dirent *de, *p_de;
- DIR *dir = NULL, *p_dir = NULL;
- FILE *f;
- sysfs_path_t path, p_path;
- unsigned int major, minor;
- char *ret = ret_path;
-
- ret_path[0] = 0;
- if ((dir = opendir("/sys/block")) == NULL)
- return NULL;
- while ((de = readdir(dir)) != NULL) {
- if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, "..") ||
- strlen(de->d_name) > sizeof(path)-32)
- continue;
- snprintf(path, SYSFS_PATH_LEN,
- "/sys/block/%s/dev", de->d_name);
- f = fopen(path, "r");
- if (f &&
- (fscanf(f, "%u:%u", &major, &minor) == 2)) {
- fclose(f); f = NULL;
- if (makedev(major, minor) == devno) {
- snprintf(ret_path, SYSFS_PATH_LEN,
- "/sys/block/%s", de->d_name);
- goto success;
- }
-#ifdef major
- if (major(devno) != major)
- continue;
-#endif
- }
- if (f)
- fclose(f);
-
- snprintf(path, SYSFS_PATH_LEN, "/sys/block/%s", de->d_name);
-
- if (p_dir)
- closedir(p_dir);
- if ((p_dir = opendir(path)) == NULL)
- continue;
- while ((p_de = readdir(p_dir)) != NULL) {
- if (!strcmp(p_de->d_name, ".") ||
- !strcmp(p_de->d_name, "..") ||
- (strlen(p_de->d_name) >
- SYSFS_PATH_LEN - strlen(path) - 32))
- continue;
- snprintf(p_path, SYSFS_PATH_LEN, "%s/%s/dev",
- path, p_de->d_name);
-
- f = fopen(p_path, "r");
- if (f &&
- (fscanf(f, "%u:%u", &major, &minor) == 2) &&
- (((major << 8) + minor) == devno)) {
- fclose(f);
- snprintf(ret_path, SYSFS_PATH_LEN, "%s/%s",
- path, p_de->d_name);
- goto success;
- }
- if (f)
- fclose(f);
- }
- }
- ret = NULL;
-success:
- if (dir)
- closedir(dir);
- if (p_dir)
- closedir(p_dir);
- return ret;
-}
-
static blk64_t get_partition_start(const char *device_name)
{
+#ifdef __linux__
unsigned long long start;
- sysfs_path_t path;
+ char path[128];
struct stat st;
FILE *f;
- char *cp;
int n;
if ((stat(device_name, &st) < 0) || !S_ISBLK(st.st_mode))
return 0;
- cp = search_sysfs_block(st.st_rdev, path);
- if (!cp)
- return 0;
- if (strlen(path) > SYSFS_PATH_LEN - sizeof("/start"))
- return 0;
- strcat(path, "/start");
+ sprintf(path, "/sys/dev/block/%d:%d/start",
+ major(st.st_rdev), minor(st.st_rdev));
f = fopen(path, "r");
if (!f)
return 0;
n = fscanf(f, "%llu", &start);
fclose(f);
return (n == 1) ? start : 0;
+#else
+ return 0;
+#endif
}
static errcode_t create_directory(ext2_filsys fs, char *dir,
base-commit: 6695555e50a374f897965300568253f242a0b13b
--
2.39.0
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