| Message ID | 20200513005424.81369-5-sandals@crustytoothpaste.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | SHA-256 part 2/3: protocol functionality | expand |
On Wed, 13 May 2020 at 02:56, brian m. carlson <sandals@crustytoothpaste.net> wrote: > diff --git a/git-compat-util.h b/git-compat-util.h > index 8ba576e81e..6503deb171 100644 > --- a/git-compat-util.h > +++ b/git-compat-util.h > @@ -868,6 +868,8 @@ char *xgetcwd(void); > FILE *fopen_for_writing(const char *path); > FILE *fopen_or_warn(const char *path, const char *mode); > > +int xstrncmpz(const char *s, const char *t, size_t len); > + > /* > * FREE_AND_NULL(ptr) is like free(ptr) followed by ptr = NULL. Note > * that ptr is used twice, so don't pass e.g. ptr++. > diff --git a/wrapper.c b/wrapper.c > index 3a1c0e0526..15a09740e7 100644 > --- a/wrapper.c > +++ b/wrapper.c > @@ -430,6 +430,18 @@ int xmkstemp(char *filename_template) > return fd; > } > > +/* > + * Like strncmp, but only return zero if s is NUL-terminated and exactly len > + * characters long. If it is not, consider it greater than t. > + */ I think this comment would be easier to find in the .h file. And since I'm already commenting... > +int xstrncmpz(const char *s, const char *t, size_t len) > +{ > + int res = strncmp(s, t, len); > + if (res) > + return res; > + return s[len] == '\0' ? 0 : 1; > +} > + > /* Adapted from libiberty's mkstemp.c. */ > > #undef TMP_MAX It's not entirely obvious from the context, but this function is inserted between some "tmp" stuff and some other "tmp" stuff. I don't think we need to bikeshed its exact home, but maybe "close to other string stuff", or at least not in the middle of the "tmp" section. Martin
diff --git a/git-compat-util.h b/git-compat-util.h index 8ba576e81e..6503deb171 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -868,6 +868,8 @@ char *xgetcwd(void); FILE *fopen_for_writing(const char *path); FILE *fopen_or_warn(const char *path, const char *mode); +int xstrncmpz(const char *s, const char *t, size_t len); + /* * FREE_AND_NULL(ptr) is like free(ptr) followed by ptr = NULL. Note * that ptr is used twice, so don't pass e.g. ptr++. diff --git a/wrapper.c b/wrapper.c index 3a1c0e0526..15a09740e7 100644 --- a/wrapper.c +++ b/wrapper.c @@ -430,6 +430,18 @@ int xmkstemp(char *filename_template) return fd; } +/* + * Like strncmp, but only return zero if s is NUL-terminated and exactly len + * characters long. If it is not, consider it greater than t. + */ +int xstrncmpz(const char *s, const char *t, size_t len) +{ + int res = strncmp(s, t, len); + if (res) + return res; + return s[len] == '\0' ? 0 : 1; +} + /* Adapted from libiberty's mkstemp.c. */ #undef TMP_MAX
When parsing capabilities for the pack protocol, there are times we'll want to compare the value of a capability to a NUL-terminated string. Since the data we're reading will be space-terminated, not NUL-terminated, we need a function that compares the two strings, but also checks that they're the same length. Otherwise, if we used strncmp to compare these strings, we might accidentally accept a parameter that was a prefix of the expected value. Add a function, xstrncmpz, that takes a NUL-terminated string and a non-NUL-terminated string, plus a length, and compares them, ensuring that they are the same length. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> --- git-compat-util.h | 2 ++ wrapper.c | 12 ++++++++++++ 2 files changed, 14 insertions(+)