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lbutils: strict string functions - abort on err

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on the conditions where these functions encounter
an unexpected error, we currently return -1

this means that the caller must check. which means
the caller won't check. nobody does. i often forget.

force the caller (me) to be correct, instead.

the current calling convention is that the real
return value is stored in a pointer, provided inside
the function signature, on a given string function,
and the function's return value is merely an indicator.

this calling convention is retained for now; the next
patch will change it, such that the real value is also
the function's return value. this is more flexible.

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe
2026-03-30 02:34:30 +01:00
parent 9d4302deb2
commit b96708bd3a
1 changed files with 90 additions and 47 deletions
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util/libreboot-utils/lib/string.c
+90 -47
View File
@@ -24,17 +24,25 @@
*/
#define ff ((size_t)-1 / 0xFF)
#define high ((ff) * 0x80)
/* NOTE:
* do not assume that a match means
* both words have null at the same
* location. see how this is handled
* e.g. in scmp.
*/
#define zeroes(x) (((x) - (ff)) & ~(x) & (high))
size_t
page_remain(const void *p)
{
/* calling sysconf repeatedly
* is folly. cache it (static)
*/
static size_t pagesz = 0;
if (!pagesz)
pagesz = pagesize(),
pagesz -= ((uintptr_t)p & (pagesz - 1));
pagesz = (size_t)pagesize();
return pagesz;
return pagesz - ((uintptr_t)p & (pagesz - 1));
}
long
@@ -122,49 +130,56 @@ scmp(const char *a,
size_t j;
size_t wa;
size_t wb;
int saved_errno = errno;
if (a == NULL ||
b == NULL ||
rval == NULL) {
errno = EFAULT;
if (if_err(a == NULL || b == NULL || rval == NULL, EFAULT))
goto err;
}
for ( ; ((uintptr_t)(a + i) % sizeof(size_t)) != 0; i++) {
if (i >= maxlen)
if (if_err(i >= maxlen, EOVERFLOW))
goto err;
else if (!ccmp(a, b, i, rval))
return 0;
goto out;
}
for ( ; i + sizeof(size_t) <= maxlen;
i += sizeof(size_t)) {
/* prevent crossing page boundary on word check */
if (page_remain(a + i) < sizeof(size_t) ||
page_remain(b + i) < sizeof(size_t))
break;
memcpy(&wa, a + i, sizeof(size_t));
memcpy(&wb, b + i, sizeof(size_t));
if (wa != wb)
for (j = 0; j < sizeof(size_t); j++)
if (!ccmp(a, b, i + j, rval))
return 0;
goto out;
if (!zeroes(wa))
continue;
*rval = 0;
return 0;
goto out;
}
for ( ; i < maxlen; i++)
if (!ccmp(a, b, i, rval))
return 0;
goto out;
err:
errno = EFAULT;
(void) set_errno(saved_errno, EFAULT);
if (rval != NULL)
*rval = -1;
err_exit(errno, "scmp");
return -1;
out:
errno = saved_errno;
return 0;
}
int ccmp(const char *a, const char *b,
@@ -173,9 +188,8 @@ int ccmp(const char *a, const char *b,
unsigned char ac;
unsigned char bc;
if (if_err(a == NULL || b == NULL, EFAULT) ||
rval == NULL)
return -1;
if (if_err(a == NULL || b == NULL || rval == NULL, EFAULT))
err_exit(errno, "ccmp");
ac = (unsigned char)a[i];
bc = (unsigned char)b[i];
@@ -197,15 +211,13 @@ slen(const char *s,
size_t maxlen,
size_t *rval)
{
int saved_errno = errno;
size_t i = 0;
size_t w;
size_t j;
if (s == NULL ||
rval == NULL) {
errno = EFAULT;
if (if_err(s == NULL || rval == NULL, EFAULT))
goto err;
}
for ( ; ((uintptr_t)(s + i) % sizeof(size_t)) != 0; i++) {
@@ -213,7 +225,7 @@ slen(const char *s,
goto err;
if (s[i] == '\0') {
*rval = i;
return 0;
goto out;
}
}
@@ -221,14 +233,13 @@ slen(const char *s,
i += sizeof(size_t)) {
memcpy(&w, s + i, sizeof(size_t));
if (!zeroes(w))
continue;
for (j = 0; j < sizeof(size_t); j++) {
if (s[i + j] == '\0') {
*rval = i + j;
return 0;
goto out;
}
}
}
@@ -236,15 +247,20 @@ slen(const char *s,
for ( ; i < maxlen; i++) {
if (s[i] == '\0') {
*rval = i;
return 0;
goto out;
}
}
err:
errno = EFAULT;
(void) set_errno(saved_errno, EFAULT);
if (rval != NULL)
*rval = 0;
err_exit(errno, "slen");
return -1;
out:
errno = saved_errno;
return 0;
}
/* strict word-based strdup */
@@ -256,21 +272,22 @@ sdup(const char *s,
size_t w;
size_t i = 0;
char *out = NULL;
int saved_errno = errno;
if (dest == NULL || *dest != NULL || s == NULL)
if (if_err(dest == NULL || *dest != NULL || s == NULL, EFAULT))
goto err;
out = smalloc(dest, max);
for ( ; ((uintptr_t)(s + i) % sizeof(size_t)) != 0; i++) {
if (i >= max)
if (if_err(i >= max, EOVERFLOW))
goto err;
out[i] = s[i];
if (s[i] == '\0') {
*dest = out;
return 0;
goto out;
}
}
@@ -290,7 +307,7 @@ sdup(const char *s,
out[i + j] = s[i + j];
if (s[i + j] == '\0') {
*dest = out;
return 0;
goto out;
}
}
}
@@ -300,7 +317,7 @@ sdup(const char *s,
out[i] = s[i];
if (s[i] == '\0') {
*dest = out;
return 0;
goto out;
}
}
@@ -308,8 +325,14 @@ err:
free_and_set_null(&out);
if (dest != NULL)
*dest = NULL;
errno = EFAULT;
(void) set_errno(saved_errno, EFAULT);
err_exit(errno, "sdup");
return -1;
out:
errno = saved_errno;
return 0;
}
/* concatenate N number of strings */
@@ -347,6 +370,7 @@ scatn(ssize_t sc, const char **sv,
rtmp = NULL;
}
errno = saved_errno;
*rval = final;
return 0;
err:
@@ -354,7 +378,10 @@ err:
free_and_set_null(&rtmp);
free_and_set_null(&final);
return set_errno(saved_errno, EFAULT);
(void) set_errno(saved_errno, EFAULT);
err_exit(errno, "scatn");
return -1;
}
/* strict strcat */
@@ -365,16 +392,16 @@ scat(const char *s1, const char *s2,
size_t size1;
size_t size2;
char *rval = NULL;
int saved_errno = errno;
if (if_err(dest == NULL || *dest != NULL, EFAULT) ||
slen(s1, n, &size1) < 0 ||
slen(s2, n, &size2) < 0 ||
if_err(size1 > SIZE_MAX - size2 - 1, EOVERFLOW)) {
if (if_err(dest == NULL || *dest != NULL, EFAULT))
goto err;
if (dest != NULL)
*dest = NULL;
return -1;
}
slen(s1, n, &size1);
slen(s2, n, &size2);
if (if_err(size1 > SIZE_MAX - size2 - 1, EOVERFLOW))
goto err;
memcpy(smalloc(&rval, size1 + size2 + 1),
s1, size1);
@@ -382,7 +409,15 @@ scat(const char *s1, const char *s2,
*(rval + size1 + size2) = '\0';
*dest = rval;
errno = saved_errno;
return 0;
err:
(void) set_errno(saved_errno, EINVAL);
if (dest != NULL)
*dest = NULL;
err_exit(errno, "scat");
return -1;
}
/* strict split/de-cat - off is where
@@ -395,14 +430,16 @@ dcat(const char *s, size_t n,
size_t size;
char *rval1 = NULL;
char *rval2 = NULL;
int saved_errno = errno;
if (dest1 == NULL || dest2 == NULL ||
slen(s, n, &size) < 0 ||
if_err(size == SIZE_MAX, EOVERFLOW) ||
if_err(off >= size, EOVERFLOW)) {
if (if_err(dest1 == NULL || dest2 == NULL, EFAULT))
goto err;
slen(s, n, &size);
if (if_err(size >= SIZE_MAX - 1, EOVERFLOW) ||
if_err(off >= size, EOVERFLOW))
goto err;
}
memcpy(smalloc(&rval1, off + 1),
s, off);
@@ -415,6 +452,7 @@ dcat(const char *s, size_t n,
*dest1 = rval1;
*dest2 = rval2;
errno = saved_errno;
return 0;
err:
@@ -423,6 +461,9 @@ err:
free_and_set_null(&rval1);
free_and_set_null(&rval2);
(void) set_errno(saved_errno, EINVAL);
err_exit(errno, "dcat");
return -1;
}
@@ -433,6 +474,7 @@ err:
int
vcmp(const void *s1, const void *s2, size_t n)
{
int saved_errno = errno;
size_t i = 0;
size_t a;
size_t b;
@@ -459,6 +501,7 @@ vcmp(const void *s1, const void *s2, size_t n)
if (x[i] != y[i])
return (int)x[i] - (int)y[i];
errno = saved_errno;
return 0;
}