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virt: simplify userns_has_mapping() by using fscanf() instead of scanf()

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And while we are at it, also fix propagation of an uninitialized errno
error.
This commit is contained in:
Lennart Poettering
2022-03-31 16:34:41 +02:00
parent 49be03838d
commit b2a331f2e0
1 changed files with 11 additions and 15 deletions
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src/basic/virt.c
+11 -15
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@@ -12,6 +12,7 @@
#include "cgroup-util.h"
#include "dirent-util.h"
#include "env-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "macro.h"
@@ -791,10 +792,7 @@ int detect_virtualization(void) {
static int userns_has_mapping(const char *name) {
_cleanup_fclose_ FILE *f = NULL;
_cleanup_free_ char *buf = NULL;
size_t n_allocated = 0;
ssize_t n;
uint32_t a, b, c;
uid_t a, b, c;
int r;
f = fopen(name, "re");
@@ -803,19 +801,17 @@ static int userns_has_mapping(const char *name) {
return errno == ENOENT ? false : -errno;
}
n = getline(&buf, &n_allocated, f);
if (n < 0) {
if (feof(f)) {
log_debug("%s is empty, we're in an uninitialized user namespace", name);
return true;
}
errno = 0;
r = fscanf(f, UID_FMT " " UID_FMT " " UID_FMT "\n", &a, &b, &c);
if (r == EOF) {
if (ferror(f))
return log_debug_errno(errno_or_else(EIO), "Failed to read %s: %m", name);
return log_debug_errno(errno, "Failed to read %s: %m", name);
log_debug("%s is empty, we're in an uninitialized user namespace", name);
return true;
}
r = sscanf(buf, "%"PRIu32" %"PRIu32" %"PRIu32, &a, &b, &c);
if (r < 3)
return log_debug_errno(errno, "Failed to parse %s: %m", name);
if (r != 3)
return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG), "Failed to parse %s: %m", name);
if (a == 0 && b == 0 && c == UINT32_MAX) {
/* The kernel calls mappings_overlap() and does not allow overlaps */