lparstat: reversed arguments to fread() in get_name()

[nathanlynch]

void get_name(const char *file, char *buf)
{
	FILE *f;
	char tmpbuf[64];
	int rc;

	f = fopen(file, "r");
	if(!f) {
		sprintf(buf, "%c", '\0');
		return;
	}
	rc = fread(tmpbuf, 64, 1, f);
	fclose(f);

	if (!rc)
		sprintf(buf, "%s", tmpbuf);
}

The fread() as used here does a partial read of a single element for any stream that yields less than 64 bytes, and the value of a partial element is unspecified according to https://pubs.opengroup.org/onlinepubs/009695399/functions/fread.html

[tyreld]

I find it funny that the example of fread in the provided reference is basically identical to what get_name does, and they store the return value as bytes_read even though that would only be the case if the size and nmemb values were reveresed.

EXAMPLES

Reading from a Stream

The following example reads a single element from the fp stream into the array pointed to by buf.

#include <stdio.h>
...
size_t bytes_read;
char buf[100];
FILE *fp;
...
bytes_read = fread(buf, sizeof(buf), 1, fp);
...

[tyreld]

Another interesting note is that the code seems to actually rely on a partial read where fread returns zero.

rc = fread(tmpbuf, 64, 1, f);
fclose(f);

if (!rc)
	sprintf(buf, "%s", tmpbuf);

If fread actually managed to read a full 64bytes then rc == 1 and we don't execute sprintf.