Hi Junio, On 6 Jan 2022, at 15:07, John Cai via GitGitGadget wrote: > From: John Cai <johncai86@xxxxxxxxx> > > There are two functions that have very similar logic of finding a header > value. find_commit_header, and find_header. We can conslidate the logic > by introducing a new function find_header_mem, which is equivalent to > find_commit_header except it takes a len parameter that determines how > many bytes will be read. find_commit_header and find_header can then both > call find_header_mem. > > This reduces duplicate logic, as the logic for finding header values > can now all live in one place. > > Signed-off-by: John Cai <johncai86@xxxxxxxxx> > --- > Consolidate find_header logic into one function > > This addresses the NEEDSWORK comment in builtin/receive-pack.c: > > /** > * NEEDSWORK: reuse find_commit_header() from jk/commit-author-parsing > * after dropping "_commit" from its name and possibly moving it out > * of commit.c > **/ > > > There are two functions that have very similar logic of finding a header > value. find_commit_header, and find_header. We can conslidate the logic > by introducing a new function find_header_mem, which is equivalent to > find_commit_header except it takes a len parameter that determines how > many bytes will be read. find_commit_header and find_header can then > both call find_header_mem. > > This reduces duplicate logic, as the logic for finding header values can > now all live in one place. > > Changes since v4: > > * adjust verbiage of NEEDSWORK comment block > > Changes since v3: > > * added NEEDSWORK block detailing what needs to be done to clean up > find_header_mem > * fixed verbiage in commit message > * adjusted style of an if block (based on Junio's feedback) > > Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1125%2Fjohn-cai%2Fjc%2Freplace-find-header-v6 > Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1125/john-cai/jc/replace-find-header-v6 > Pull-Request: https://github.com/git/git/pull/1125 > > Range-diff vs v5: > > 1: 02da3136c43 ! 1: 2b01d92b951 receive-pack.c: consolidate find header logic > @@ commit.c: struct commit_list **commit_list_append(struct commit *commit, > + * NEEDSWORK: It's possible for strchrnul() to scan beyond the range > + * given by len. However, current callers are safe because they compute > + * len by scanning a NUL-terminated block of memory starting at msg. > -+ * Make this function safer by checking if the input is NUL-terminated > -+ * or has a NL between line[0] and msg[len]. > ++ * Nonetheless, it would be better to ensure the function does not look > ++ * at msg beyond the len provided by the caller. > + */ > + while (line && line < msg + len) { > const char *eol = strchrnul(line, '\n'); > > > builtin/receive-pack.c | 33 ++++++++++----------------------- > commit.c | 16 ++++++++++++++-- > commit.h | 5 +++++ > 3 files changed, 29 insertions(+), 25 deletions(-) > > diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c > index 9f4a0b816cf..5c2732a0d07 100644 > --- a/builtin/receive-pack.c > +++ b/builtin/receive-pack.c > @@ -581,32 +581,19 @@ static char *prepare_push_cert_nonce(const char *path, timestamp_t stamp) > return strbuf_detach(&buf, NULL); > } > > -/* > - * NEEDSWORK: reuse find_commit_header() from jk/commit-author-parsing > - * after dropping "_commit" from its name and possibly moving it out > - * of commit.c > - */ > static char *find_header(const char *msg, size_t len, const char *key, > const char **next_line) > { > - int key_len = strlen(key); > - const char *line = msg; > - > - while (line && line < msg + len) { > - const char *eol = strchrnul(line, '\n'); > - > - if ((msg + len <= eol) || line == eol) > - return NULL; > - if (line + key_len < eol && > - !memcmp(line, key, key_len) && line[key_len] == ' ') { > - int offset = key_len + 1; > - if (next_line) > - *next_line = *eol ? eol + 1 : eol; > - return xmemdupz(line + offset, (eol - line) - offset); > - } > - line = *eol ? eol + 1 : NULL; > - } > - return NULL; > + size_t out_len; > + const char *val = find_header_mem(msg, len, key, &out_len); > + > + if (!val) > + return NULL; > + > + if (next_line) > + *next_line = val + out_len + 1; > + > + return xmemdupz(val, out_len); > } > > /* > diff --git a/commit.c b/commit.c > index a348f085b2b..28391c3468d 100644 > --- a/commit.c > +++ b/commit.c > @@ -1631,12 +1631,20 @@ struct commit_list **commit_list_append(struct commit *commit, > return &new_commit->next; > } > > -const char *find_commit_header(const char *msg, const char *key, size_t *out_len) > +const char *find_header_mem(const char *msg, size_t len, > + const char *key, size_t *out_len) > { > int key_len = strlen(key); > const char *line = msg; > > - while (line) { > + /* > + * NEEDSWORK: It's possible for strchrnul() to scan beyond the range > + * given by len. However, current callers are safe because they compute > + * len by scanning a NUL-terminated block of memory starting at msg. > + * Nonetheless, it would be better to ensure the function does not look > + * at msg beyond the len provided by the caller. > + */ Let me know if this verbiage makes sense. > + while (line && line < msg + len) { > const char *eol = strchrnul(line, '\n'); > > if (line == eol) > @@ -1653,6 +1661,10 @@ const char *find_commit_header(const char *msg, const char *key, size_t *out_len > return NULL; > } > > +const char *find_commit_header(const char *msg, const char *key, size_t *out_len) > +{ > + return find_header_mem(msg, strlen(msg), key, out_len); > +} > /* > * Inspect the given string and determine the true "end" of the log message, in > * order to find where to put a new Signed-off-by trailer. Ignored are > diff --git a/commit.h b/commit.h > index 3ea32766bcb..38cc5426615 100644 > --- a/commit.h > +++ b/commit.h > @@ -290,12 +290,17 @@ void free_commit_extra_headers(struct commit_extra_header *extra); > > /* > * Search the commit object contents given by "msg" for the header "key". > + * Reads up to "len" bytes of "msg". > * Returns a pointer to the start of the header contents, or NULL. The length > * of the header, up to the first newline, is returned via out_len. > * > * Note that some headers (like mergetag) may be multi-line. It is the caller's > * responsibility to parse further in this case! > */ > +const char *find_header_mem(const char *msg, size_t len, > + const char *key, > + size_t *out_len); > + > const char *find_commit_header(const char *msg, const char *key, > size_t *out_len); > > > base-commit: c8b2ade48c204690119936ada89cd938c476c5c2 > -- > gitgitgadget
