strerror

Convert an error number into an error message (reentrant)

Synopsis:

#include <string.h>

int strerror_r( int errnum,
                char *strerrbuf,
                size_t buflen );

Arguments:

errnum: The error number that you want the message for. This function works for any valid errno value.
strerrbuf: A pointer to a buffer where the function can store the error message.
buflen: The length of the buffer, in bytes.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The strerror_r() function maps the error number contained in errnum to an error message, which it stores in the buffer that strerrbuf points to.

Returns:

0: Success.
EINVAL: The value of errnum isn't a valid error number.
ERANGE: The buffer pointed to by strerrbuf isn't big enough to hold the generated message string.

Examples:

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>

#define MSG_LEN 100

int main( void )
{
   FILE *fp;
   char msg_buff[MSG_LEN];
   int error_num;

   fp = fopen( "file.name", "r" );
   if( fp == NULL ) {
      error_num = strerror_r ( errno, msg_buff, MSG_LEN);

      switch (error_num) {
         case 0:
            printf( "Unable to open file: %s\n", msg_buff);
            break;

         case EINVAL:
            printf ( "strerror_r() failed: invalid error code, %d\n",
                     error_num);
            break;

         case ERANGE:
            printf ( "strerror_r() failed: buffer too small: %d\n",
                    MSG_LEN);
            break;

       }
   }
   return EXIT_SUCCESS;
}

Classification:

POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes