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misc/mk_hugefiles: simplify get_partition_start()

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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@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Eric Biggers 2023-01-21 12:32:23 -08:00 committed by Theodore Ts'o
parent 44ee1fb80b
commit 4d890149b9
2 changed files with 10 additions and 132 deletions
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8
include/mingw/sys/sysmacros.h
View File

@ -1,11 +1,5 @@
#pragma once
/*
* 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
#endif

134
misc/mk_hugefiles.c
View File

@ -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 +63,30 @@ 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)
static blk64_t
get_partition_start(const char *device_name EXT2FS_ATTR((unused)))
{
#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,