libpayload: Deduplicate strtol and strtoull

Our strtol() and strtoull() function contain almost exactly the same
code. This is a) bad in general and b) may cause the code to get out of
sync, such as it recently happened with CB:32029.

This patch changes strtol() to be based on strtoull() so that the main
parsing code exists only once, and also adds a strtoll() to round off
the library. Also fix the bounds imposed by strtoul() to be based on the
actual length of a 'long', not hardcoded to 32-bits (which is not
equivalent on all architectures).

Change-Id: I919c65a773cecdb11739c3f22dd0d182ed50c07f
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32086
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

2 files changed, 26 insertions, 40 deletions

diff --git a/payloads/libpayload/include/stdlib.h b/payloads/libpayload/include/stdlib.h
index 3f94d2119a00..06fb735b75a2 100644
--- a/payloads/libpayload/include/stdlib.h
+++ b/payloads/libpayload/include/stdlib.h
@@ -186,6 +186,7 @@ static inline void *xmemalign_work(size_t align, size_t size, const char *file,
  * @{
  */
 long int strtol(const char *s, char **nptr, int base);
+long long int strtoll(const char *s, char **nptr, int base);
 unsigned long int strtoul(const char *s, char **nptr, int base);
 unsigned long long int strtoull(const char *s, char **nptr, int base);
 long atol(const char *nptr);
diff --git a/payloads/libpayload/libc/string.c b/payloads/libpayload/libc/string.c
index f563f6338a39..6c257cbdaa76 100644
--- a/payloads/libpayload/libc/string.c
+++ b/payloads/libpayload/libc/string.c
@@ -33,6 +33,7 @@
 #include <string.h>
 #include <ctype.h>
 #include <inttypes.h>
+#include <limits.h>
 #include <errno.h>
 
 /**
@@ -419,59 +420,43 @@ static int _offset(char ch, int base)
  * @return A signed integer representation of the string
  */
 
-long int strtol(const char *ptr, char **endptr, int base)
+long long int strtoll(const char *orig_ptr, char **endptr, int base)
 {
-	int ret = 0;
-	int negative = 1;
-
-	if (endptr != NULL)
-		*endptr = (char *) ptr;
+	const char *ptr = orig_ptr;
+	int is_negative = 0;
 
 	/* Purge whitespace */
 
 	for( ; *ptr && isspace(*ptr); ptr++);
 
 	if (ptr[0] == '-') {
-		negative = -1;
+		is_negative = 1;
 		ptr++;
 	}
 
-	if (!*ptr)
-		return 0;
+	unsigned long long uval = strtoull(ptr, endptr, base);
 
-	/* Determine the base */
+	/* If the whole string is unparseable, endptr should point to start. */
+	if (endptr && *endptr == ptr)
+		*endptr = (char *)orig_ptr;
 
-	if (base == 0) {
-		if (ptr[0] == '0' && (ptr[1] == 'x' || ptr[1] == 'X'))
-			base = 16;
-		else if (ptr[0] == '0') {
-			base = 8;
-			ptr++;
-		}
-		else
-			base = 10;
-	}
-
-	/* Base 16 allows the 0x on front - so skip over it */
+	if (uval > (unsigned long long)LLONG_MAX + !!is_negative)
+		uval = (unsigned long long)LLONG_MAX + !!is_negative;
 
-	if (base == 16) {
-		if (ptr[0] == '0' && (ptr[1] == 'x' || ptr[1] == 'X'))
-			ptr += 2;
-	}
-
-	/* If the first character isn't valid, then don't
-	 * bother */
-
-	if (!*ptr || !_valid(*ptr, base))
-		return 0;
-
-	for( ; *ptr && _valid(*ptr, base); ptr++)
-		ret = (ret * base) + _offset(*ptr, base);
-
-	if (endptr != NULL)
-		*endptr = (char *) ptr;
+	if (is_negative)
+		return -uval;
+	else
+		return uval;
+}
 
-	return ret * negative;
+long int strtol(const char *ptr, char **endptr, int base)
+{
+	long long int val = strtoll(ptr, endptr, base);
+	if (val > LONG_MAX)
+		return LONG_MAX;
+	if (val < LONG_MIN)
+		return LONG_MIN;
+	return val;
 }
 
 long atol(const char *nptr)
@@ -534,7 +519,7 @@ unsigned long long int strtoull(const char *ptr, char **endptr, int base)
 unsigned long int strtoul(const char *ptr, char **endptr, int base)
 {
 	unsigned long long val = strtoull(ptr, endptr, base);
-	if (val > UINT32_MAX) return UINT32_MAX;
+	if (val > ULONG_MAX) return ULONG_MAX;
 	return val;
 }