Fix assorted infelicities in new SetWALSegSize() function.

tglsfdc · tglsfdc · commit 8485a25a8c9a · 2017-09-24T12:05:06.000-04:00
* Failure to check for malloc failure (ok, pretty unlikely here, but
that's not an excuse).

* Leakage of open fd on read error, and of malloc'd buffer always.

* Incorrect assumption that a short read would set errno to zero.

* Failure to adhere to message style conventions (in particular,
not reporting errno where relevant; using "couldn't open" rather than
"could not open" is not really in line with project style either).

* Missing newlines on some messages.

Coverity spotted the leak problems; I noticed the rest while
fixing the leaks.
diff --git a/contrib/pg_standby/pg_standby.c b/contrib/pg_standby/pg_standby.c
@@ -408,16 +408,21 @@ SetWALSegSize(void)
 {
 	bool		ret_val = false;
 	int			fd;
-	char	   *buf = (char *) malloc(XLOG_BLCKSZ);
+
+	/* malloc this buffer to ensure sufficient alignment: */
+	char	   *buf = (char *) pg_malloc(XLOG_BLCKSZ);
 
 	Assert(WalSegSz == -1);
 
 	if ((fd = open(WALFilePath, O_RDWR, 0)) < 0)
 	{
-		fprintf(stderr, "%s: couldn't open WAL file \"%s\"\n",
-				progname, WALFilePath);
+		fprintf(stderr, "%s: could not open WAL file \"%s\": %s\n",
+				progname, WALFilePath, strerror(errno));
+		pg_free(buf);
 		return false;
 	}
+
+	errno = 0;
 	if (read(fd, buf, XLOG_BLCKSZ) == XLOG_BLCKSZ)
 	{
 		XLogLongPageHeader longhdr = (XLogLongPageHeader) buf;
@@ -433,7 +438,6 @@ SetWALSegSize(void)
 			fprintf(stderr,
 					"%s: WAL segment size must be a power of two between 1MB and 1GB, but the WAL file header specifies %d bytes\n",
 					progname, WalSegSz);
-		close(fd);
 	}
 	else
 	{
@@ -444,17 +448,21 @@ SetWALSegSize(void)
 		if (errno != 0)
 		{
 			if (debug)
-				fprintf(stderr, "could not read file \"%s\": %s",
+				fprintf(stderr, "could not read file \"%s\": %s\n",
 						WALFilePath, strerror(errno));
 		}
 		else
 		{
 			if (debug)
-				fprintf(stderr, "not enough data in file \"%s\"", WALFilePath);
+				fprintf(stderr, "not enough data in file \"%s\"\n",
+						WALFilePath);
 		}
 	}
 
 	fflush(stderr);
+
+	close(fd);
+	pg_free(buf);
 	return ret_val;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -408,16 +408,21 @@ SetWALSegSize(void)`
`408`	`408`	`{`
`409`	`409`	`bool ret_val = false;`
`410`	`410`	`int fd;`
`411`		`- char buf = (char ) malloc(XLOG_BLCKSZ);`
	`411`	`+`
	`412`	`+ /* malloc this buffer to ensure sufficient alignment: */`
	`413`	`+ char buf = (char ) pg_malloc(XLOG_BLCKSZ);`
`412`	`414`
`413`	`415`	`Assert(WalSegSz == -1);`
`414`	`416`
`415`	`417`	`if ((fd = open(WALFilePath, O_RDWR, 0)) < 0)`
`416`	`418`	`{`
`417`		`- fprintf(stderr, "%s: couldn't open WAL file \"%s\"\n",`
`418`		`- progname, WALFilePath);`
	`419`	`+ fprintf(stderr, "%s: could not open WAL file \"%s\": %s\n",`
	`420`	`+ progname, WALFilePath, strerror(errno));`
	`421`	`+ pg_free(buf);`
`419`	`422`	`return false;`
`420`	`423`	`}`
	`424`	`+`
	`425`	`+ errno = 0;`
`421`	`426`	`if (read(fd, buf, XLOG_BLCKSZ) == XLOG_BLCKSZ)`
`422`	`427`	`{`
`423`	`428`	`XLogLongPageHeader longhdr = (XLogLongPageHeader) buf;`
`@@ -433,7 +438,6 @@ SetWALSegSize(void)`
`433`	`438`	`fprintf(stderr,`
`434`	`439`	`"%s: WAL segment size must be a power of two between 1MB and 1GB, but the WAL file header specifies %d bytes\n",`
`435`	`440`	`progname, WalSegSz);`
`436`		`- close(fd);`
`437`	`441`	`}`
`438`	`442`	`else`
`439`	`443`	`{`
`@@ -444,17 +448,21 @@ SetWALSegSize(void)`
`444`	`448`	`if (errno != 0)`
`445`	`449`	`{`
`446`	`450`	`if (debug)`
`447`		`- fprintf(stderr, "could not read file \"%s\": %s",`
	`451`	`+ fprintf(stderr, "could not read file \"%s\": %s\n",`
`448`	`452`	`WALFilePath, strerror(errno));`
`449`	`453`	`}`
`450`	`454`	`else`
`451`	`455`	`{`
`452`	`456`	`if (debug)`
`453`		`- fprintf(stderr, "not enough data in file \"%s\"", WALFilePath);`
	`457`	`+ fprintf(stderr, "not enough data in file \"%s\"\n",`
	`458`	`+ WALFilePath);`
`454`	`459`	`}`
`455`	`460`	`}`
`456`	`461`
`457`	`462`	`fflush(stderr);`
	`463`	`+`
	`464`	`+ close(fd);`
	`465`	`+ pg_free(buf);`
`458`	`466`	`return ret_val;`
`459`	`467`	`}`
`460`	`468`