config: require at least one digit when parsing numbers

If the input to strtoimax() or strtoumax() does not contain any digits
then they return zero and set `end` to point to the start of the input
string.  git_parse_[un]signed() do not check `end` and so fail to return
an error and instead return a value of zero if the input string is a
valid units factor without any digits (e.g "k").

Tests are added to check that 'git config --int' and OPT_MAGNITUDE()
reject a units specifier without a leading digit.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/config.c b/config.c
index d5069d4f01..b7fb68026d 100644
--- a/config.c
+++ b/config.c
@@ -1167,6 +1167,10 @@ static int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
 		val = strtoimax(value, &end, 0);
 		if (errno == ERANGE)
 			return 0;
+		if (end == value) {
+			errno = EINVAL;
+			return 0;
+		}
 		factor = get_unit_factor(end);
 		if (!factor) {
 			errno = EINVAL;
@@ -1202,6 +1206,10 @@ static int git_parse_unsigned(const char *value, uintmax_t *ret, uintmax_t max)
 		val = strtoumax(value, &end, 0);
 		if (errno == ERANGE)
 			return 0;
+		if (end == value) {
+			errno = EINVAL;
+			return 0;
+		}
 		factor = get_unit_factor(end);
 		if (!factor) {
 			errno = EINVAL;