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| author | Robert Haas <rhaas@postgresql.org> | 2024-08-16 13:34:18 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2024-08-16 13:45:23 -0400 |
| commit | 76dd015e859845fc5fe60557328e3a6bbf11be31 (patch) | |
| tree | 3a6889972746f90a2a4379adf892db3fa6c90cd4 /src | |
| parent | b8b3f861fbd7ff40055225ec48cec97df925ff04 (diff) | |
| download | postgresql-76dd015e859845fc5fe60557328e3a6bbf11be31.tar.gz postgresql-76dd015e859845fc5fe60557328e3a6bbf11be31.zip | |
Improve more comments in astreamer_gzip.c.
Duplicate the comment from astreamer_plain_writer_new instead of just
referring to it. Add a further note to mention that there are dangers
if anything else is written to the same FILE. Also add a comment where
we dup() the filehandle, referring to the existing comment in
astreamer_gzip_writer_finalize(), because the dup() looks wrong on
first glance without that comment to clarify.
Per concerns expressed by Tom Lane on pgsql-security, and using
some wording suggested by him.
Discussion: http://postgr.es/m/CA+TgmoYTFAD0YTh4HC1Nuhn0YEyoQi0_CENFgVzAY_YReiSksQ@mail.gmail.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/fe_utils/astreamer_gzip.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/src/fe_utils/astreamer_gzip.c b/src/fe_utils/astreamer_gzip.c index ed9ec50fedd..0d12b9bce7a 100644 --- a/src/fe_utils/astreamer_gzip.c +++ b/src/fe_utils/astreamer_gzip.c @@ -86,9 +86,16 @@ static const astreamer_ops astreamer_gzip_decompressor_ops = { * Create a astreamer that just compresses data using gzip, and then writes * it to a file. * - * As in the case of astreamer_plain_writer_new, pathname is always used - * for error reporting purposes; if file is NULL, it is also the opened and - * closed so that the data may be written there. + * The caller must specify a pathname and may specify a file. The pathname is + * used for error-reporting purposes either way. If file is NULL, the pathname + * also identifies the file to which the data should be written: it is opened + * for writing and closed when done. If file is not NULL, the data is written + * there. + * + * Note that zlib does not use the FILE interface, but operates directly on + * a duplicate of the underlying fd. Hence, callers must take care if they + * plan to write any other data to the same FILE, either before or after using + * this. */ astreamer * astreamer_gzip_writer_new(char *pathname, FILE *file, @@ -112,6 +119,10 @@ astreamer_gzip_writer_new(char *pathname, FILE *file, } else { + /* + * We must dup the file handle so that gzclose doesn't break the + * caller's FILE. See comment for astreamer_gzip_writer_finalize. + */ int fd = dup(fileno(file)); if (fd < 0) |