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util/nvmutil: portable, secure strlen function

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xstrxlen ftw

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe
2026-03-08 14:27:27 +00:00
parent 9be83fa034
commit 10507e1436
1 changed files with 35 additions and 2 deletions
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util/nvmutil/nvmutil.c
+35 -2
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@@ -75,6 +75,7 @@ static void set_part_modified(size_t p);
static void check_part_num(size_t p);
static void usage(void);
static size_t xstrxlen(const char *scmp, size_t maxlen);
static int xstrxcmp(const char *a, const char *b, size_t maxlen);
static void err(int nvm_errval, const char *msg, ...);
static const char *getnvmprogname(void);
static void set_err(int errval);
@@ -372,7 +373,8 @@ set_cmd(int argc, char *argv[])
if (argc < 3)
break;
if (strcmp(argv[2], command[cmd_index].str) != 0)
if (xstrxcmp(argv[2], command[cmd_index].str,
MAX_CMD_LEN) != 0)
continue;
if (argc >= command[cmd_index].argc)
@@ -488,7 +490,7 @@ set_io_flags(int argc, char *argv[])
if (argc < 3)
return;
if (strcmp(argv[2], "dump") == 0)
if (xstrxcmp(argv[2], "dump", MAX_CMD_LEN) == 0)
gbe_flags = O_RDONLY;
}
@@ -1118,6 +1120,37 @@ xstrxlen(const char *scmp, size_t maxlen)
return xstr_index;
}
/*
* Portable, secure strcmp() with the same mentality
* as our xstrxlen
*/
static int
xstrxcmp(const char *a, const char *b, size_t maxlen)
{
size_t i;
if (!a || !b)
err(EINVAL, "NULL input to xstrxcmp");
if (*a == '\0' || *b == '\0')
err(EINVAL, "Empty string in xstrxcmp");
for (i = 0; i < maxlen; i++) {
if (a[i] != b[i])
return (unsigned char)a[i] - (unsigned char)b[i];
if (a[i] == '\0')
return 0;
}
err(EINVAL, "Unterminated string in xstrxcmp");
/*
* Should never reach here. This keeps compilers happy.
*/
return -1;
}
static void
err(int nvm_errval, const char *msg, ...)
{