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Suppress -Wunused-result warnings about write() and fwrite().

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This is merely an exercise in satisfying pedants, not a bug fix, because
in every case we were checking for failure later with ferror(), or else
there was nothing useful to be done about a failure anyway.  Document
the latter cases.
This commit is contained in:
Tom Lane 2011-10-18 21:37:51 -04:00
parent c53d3a9ee1
commit aa90e148ca
5 changed files with 59 additions and 19 deletions
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6
src/backend/access/transam/xlog.c
View File

@ -9067,8 +9067,10 @@ do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile)
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m",
BACKUP_LABEL_FILE)));
fwrite(labelfbuf.data, labelfbuf.len, 1, fp);
if (fflush(fp) || ferror(fp) || FreeFile(fp))
if (fwrite(labelfbuf.data, labelfbuf.len, 1, fp) != 1 ||
fflush(fp) != 0 ||
ferror(fp) ||
FreeFile(fp))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write file \"%s\": %m",

6
src/backend/commands/copy.c
View File

@ -466,9 +466,9 @@ CopySendEndOfRow(CopyState cstate)
#endif
}
(void) fwrite(fe_msgbuf->data, fe_msgbuf->len,
1, cstate->copy_file);
if (ferror(cstate->copy_file))
if (fwrite(fe_msgbuf->data, fe_msgbuf->len, 1,
cstate->copy_file) != 1 ||
ferror(cstate->copy_file))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to COPY file: %m")));

16
src/backend/postmaster/pgstat.c
View File

@ -3284,6 +3284,7 @@ pgstat_write_statsfile(bool permanent)
int32 format_id;
const char *tmpfile = permanent ? PGSTAT_STAT_PERMANENT_TMPFILE : pgstat_stat_tmpname;
const char *statfile = permanent ? PGSTAT_STAT_PERMANENT_FILENAME : pgstat_stat_filename;
int rc;
/*
* Open the statistics temp file to write out the current values.
@ -3307,12 +3308,14 @@ pgstat_write_statsfile(bool permanent)
* Write the file header --- currently just a format ID.
*/
format_id = PGSTAT_FILE_FORMAT_ID;
fwrite(&format_id, sizeof(format_id), 1, fpout);
rc = fwrite(&format_id, sizeof(format_id), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Write global stats struct
*/
fwrite(&globalStats, sizeof(globalStats), 1, fpout);
rc = fwrite(&globalStats, sizeof(globalStats), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Walk through the database table.
@ -3326,7 +3329,8 @@ pgstat_write_statsfile(bool permanent)
* use to any other process.
*/
fputc('D', fpout);
fwrite(dbentry, offsetof(PgStat_StatDBEntry, tables), 1, fpout);
rc = fwrite(dbentry, offsetof(PgStat_StatDBEntry, tables), 1, fpout);
(void) rc; /* we'll check for error with ferror */
/*
* Walk through the database's access stats per table.
@ -3335,7 +3339,8 @@ pgstat_write_statsfile(bool permanent)
while ((tabentry = (PgStat_StatTabEntry *) hash_seq_search(&tstat)) != NULL)
{
fputc('T', fpout);
fwrite(tabentry, sizeof(PgStat_StatTabEntry), 1, fpout);
rc = fwrite(tabentry, sizeof(PgStat_StatTabEntry), 1, fpout);
(void) rc; /* we'll check for error with ferror */
}
/*
@ -3345,7 +3350,8 @@ pgstat_write_statsfile(bool permanent)
while ((funcentry = (PgStat_StatFuncEntry *) hash_seq_search(&fstat)) != NULL)
{
fputc('F', fpout);
fwrite(funcentry, sizeof(PgStat_StatFuncEntry), 1, fpout);
rc = fwrite(funcentry, sizeof(PgStat_StatFuncEntry), 1, fpout);
(void) rc; /* we'll check for error with ferror */
}
/*

38
src/backend/utils/error/elog.c
View File

@ -1747,10 +1747,12 @@ write_eventlog(int level, const char *line, int len)
static void
write_console(const char *line, int len)
{
int rc;
#ifdef WIN32
/*
* WriteConsoleW() will fail of stdout is redirected, so just fall through
* WriteConsoleW() will fail if stdout is redirected, so just fall through
* to writing unconverted to the logfile in this case.
*
* Since we palloc the structure required for conversion, also fall
@ -1788,13 +1790,18 @@ write_console(const char *line, int len)
#else
/*
* Conversion on non-win32 platform is not implemented yet. It requires
* Conversion on non-win32 platforms is not implemented yet. It requires
* non-throw version of pg_do_encoding_conversion(), that converts
* unconvertable characters to '?' without errors.
*/
#endif
write(fileno(stderr), line, len);
/*
* We ignore any error from write() here. We have no useful way to report
* it ... certainly whining on stderr isn't likely to be productive.
*/
rc = write(fileno(stderr), line, len);
(void) rc;
}
/*
@ -2457,13 +2464,30 @@ send_message_to_server_log(ErrorData *edata)
/*
* Send data to the syslogger using the chunked protocol
*
* Note: when there are multiple backends writing into the syslogger pipe,
* it's critical that each write go into the pipe indivisibly, and not
* get interleaved with data from other processes. Fortunately, the POSIX
* spec requires that writes to pipes be atomic so long as they are not
* more than PIPE_BUF bytes long. So we divide long messages into chunks
* that are no more than that length, and send one chunk per write() call.
* The collector process knows how to reassemble the chunks.
*
* Because of the atomic write requirement, there are only two possible
* results from write() here: -1 for failure, or the requested number of
* bytes. There is not really anything we can do about a failure; retry would
* probably be an infinite loop, and we can't even report the error usefully.
* (There is noplace else we could send it!) So we might as well just ignore
* the result from write(). However, on some platforms you get a compiler
* warning from ignoring write()'s result, so do a little dance with casting
* rc to void to shut up the compiler.
*/
static void
write_pipe_chunks(char *data, int len, int dest)
{
PipeProtoChunk p;
int fd = fileno(stderr);
int rc;
Assert(len > 0);
@ -2476,7 +2500,8 @@ write_pipe_chunks(char *data, int len, int dest)
p.proto.is_last = (dest == LOG_DESTINATION_CSVLOG ? 'F' : 'f');
p.proto.len = PIPE_MAX_PAYLOAD;
memcpy(p.proto.data, data, PIPE_MAX_PAYLOAD);
write(fd, &p, PIPE_HEADER_SIZE + PIPE_MAX_PAYLOAD);
rc = write(fd, &p, PIPE_HEADER_SIZE + PIPE_MAX_PAYLOAD);
(void) rc;
data += PIPE_MAX_PAYLOAD;
len -= PIPE_MAX_PAYLOAD;
}
@ -2485,7 +2510,8 @@ write_pipe_chunks(char *data, int len, int dest)
p.proto.is_last = (dest == LOG_DESTINATION_CSVLOG ? 'T' : 't');
p.proto.len = len;
memcpy(p.proto.data, data, len);
write(fd, &p, PIPE_HEADER_SIZE + len);
rc = write(fd, &p, PIPE_HEADER_SIZE + len);
(void) rc;
}

12
src/bin/psql/common.c
View File

@ -228,6 +228,7 @@ static void
handle_sigint(SIGNAL_ARGS)
{
int save_errno = errno;
int rc;
char errbuf[256];
/* if we are waiting for input, longjmp out of it */
@ -244,11 +245,16 @@ handle_sigint(SIGNAL_ARGS)
if (cancelConn != NULL)
{
if (PQcancel(cancelConn, errbuf, sizeof(errbuf)))
write_stderr("Cancel request sent\n");
{
rc = write_stderr("Cancel request sent\n");
(void) rc; /* ignore errors, nothing we can do here */
}
else
{
write_stderr("Could not send cancel request: ");
write_stderr(errbuf);
rc = write_stderr("Could not send cancel request: ");
(void) rc; /* ignore errors, nothing we can do here */
rc = write_stderr(errbuf);
(void) rc; /* ignore errors, nothing we can do here */
}
}