Quoth markwalters1009 on Nov 24 at 1:20 pm: > From: Mark Walters <markwalters1009@gmail.com> > > After this series there will be times when a caller will want to pass > a very large query string to notmuch (eg a list of 10,000 message-ids) > and this can exceed the size of ARG_MAX. Hence allow notmuch to take > the query from stdin (if the query is -). > --- > query-string.c | 41 +++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 41 insertions(+), 0 deletions(-) > > diff --git a/query-string.c b/query-string.c > index 6536512..b1fbdeb 100644 > --- a/query-string.c > +++ b/query-string.c > @@ -20,6 +20,44 @@ > > #include "notmuch-client.h" > > +/* Read a single query string from STDIN, using > + * 'ctx' as the talloc owner for all allocations. > + * > + * This function returns NULL in case of insufficient memory or read > + * errors. > + */ > +static char * > +query_string_from_stdin (void *ctx) > +{ > + char *query_string; > + char buf[4096]; > + ssize_t remain; > + > + query_string = talloc_strdup (ctx, ""); > + if (query_string == NULL) > + return NULL; > + > + for (;;) { > + remain = read (STDIN_FILENO, buf, sizeof(buf) - 1); > + if (remain == 0) > + break; > + if (remain < 0) { > + if (errno == EINTR) > + continue; > + fprintf (stderr, "Error: reading from standard input: %s\n", > + strerror (errno)); talloc_free (query_string) ? > + return NULL; > + } > + > + buf[remain] = '\0'; > + query_string = talloc_strdup_append (query_string, buf); Eliminate the NUL in buf and instead talloc_strndup_append (query_string, buf, remain) ? Should there be some (large) bound on the size of the query string to prevent runaway? > + if (query_string == NULL) Technically it would be good to talloc_free the old pointer here, too. > + return NULL; > + } > + > + return query_string; > +} > + This whole approach is O(n^2), which might actually matter for large query strings. How about (tested, but only a little): #define MAX_QUERY_STRING_LENGTH (16 * 1024 * 1024) /* Read a single query string from STDIN, using 'ctx' as the talloc * owner for all allocations. * * This function returns NULL in case of insufficient memory or read * errors. */ static char * query_string_from_stdin (void *ctx) { char *query_string = NULL, *new_qs; size_t pos = 0, end = 0; ssize_t got; for (;;) { if (end - pos < 512) { end = MAX(end * 2, 1024); if (end >= MAX_QUERY_STRING_LENGTH) { fprintf (stderr, "Error: query too long\n"); goto FAIL; } new_qs = talloc_realloc (ctx, query_string, char, end); if (new_qs == NULL) goto FAIL; query_string = new_qs; } got = read (STDIN_FILENO, query_string + pos, end - pos - 1); if (got == 0) break; if (got < 0) { if (errno == EINTR) continue; fprintf (stderr, "Error: reading from standard input: %s\n", strerror (errno)); goto FAIL; } pos += got; } query_string[pos] = '\0'; return query_string; FAIL: talloc_free (query_string); return NULL; } > /* Construct a single query string from the passed arguments, using > * 'ctx' as the talloc owner for all allocations. > * > @@ -35,6 +73,9 @@ query_string_from_args (void *ctx, int argc, char *argv[]) > char *query_string; > int i; > > + if ((argc == 1) && (strcmp ("-", argv[0]) == 0)) > + return query_string_from_stdin (ctx); > + > query_string = talloc_strdup (ctx, ""); > if (query_string == NULL) > return NULL;