# gfs_pio_readline

## Name

gfs_pio_readline -- read one line

## Synopsis

    #include <gfarm/gfarm.h>

```char *gfs_pio_readline``(GFS_File `f`, char **`bufp`, size_t *`sizep`, size_t *`lenp`);`

## DESCRIPTION

`gfs_pio_readline()` reads one line from the file specified by the parameter `gf`.

Parameter `bufp` specifies an address of a pointer variable initialzed by NULL at first. `gfs_pio_readline()` allocates a buffer for I/O dynamically, and stores the address of the buffer to this variable pointed by `bufp`. Parameter `sizep` specifies an address of a size_t variable initialized by 0. This size_t variable is used to record the size of the buffer. Or, you can specify a buffer allocated by malloc(3) in the variable pointed by the parameter `bufp`. In this case, you have to specify the size of the allocated buffer by the parameter `sizep`. If the length of the line exceeds the size of the buffer, the buffer will be automatically realloc(3)ed, and the variable pointed by `bufp` and `sizep` will be updated respectively. Note that you are responsible to free(3) this buffer.

This function returns the length of the line to a variable pointed by the parameter `lenp`. This length includes newline character.

Just like gfs_pio_gets(3), this function doesn't remove newline character at the end of lines. Also, this function always appends '\0' at the end of strings. You can deal with lines which include '\0' character by using the variable pointed by the parameter `lenp`.

If the file reaches its end, the length of the result string becomes 0.

This function is equivalent to gfs_pio_readdelim(f, bufp, sizep, lenp, "\n", 1).

## RETURN VALUES

`NULL`

  The function terminated successfully.

`GFARM_ERR_NO_MEMORY`

  Insufficient memory was available.

  Note that you need to free(3) the buffer pointed by the parameter `bufp`

Others

  An error except the above occurred. The reason is shown by its pointed strings.

## EXAMPLES

Example 1. Example of `gfs_pio_readline` function

    #include <stdio.h>
    #include <stdlib.h>
    #include <gfarm/gfarm.h>

    int
    main(int argc, char **argv)
    {
    	char *e;
    	GFS_File gf;
    	size_t bufsize = 0, len;
    	char *buffer = NULL;

    	e = gfarm_initialize(&argc, &argv);
    	if (e != NULL) {
    		fprintf(stderr, "gfarm_initialize: %s\n", e);
    		return (EXIT_FAILURE);
    	}
    	if (argc <= 1) {
    		fprintf(stderr, "missing gfarm filename\n");
    		return (EXIT_FAILURE);
    	}
    	e = gfs_pio_open(argv[1], GFARM_FILE_RDONLY, &gf);
    	if (e != NULL) {
    		fprintf(stderr, "%s: %s\n", argv[1], e);
    		return (EXIT_FAILURE);
    	}
    	e = gfs_pio_set_view_global(gf, 0);
    	if (e != NULL) {
    		fprintf(stderr, "%s: gfs_pio_set_view_global: %s\n",
    		    argv[1], e);
    		return (EXIT_FAILURE);
    	}

    	while ((e = gfs_pio_readline(gf, &buffer, &bufsize, &len))
    	    == NULL && len > 0) {
    		printf("<%6d/%6d >%s", len, bufsize, buffer);
    	}
    	if (buffer != NULL)
    		free(buffer);
    	if (e != NULL) {
    		fprintf(stderr, "ERROR: %s\n", e);
    		return (EXIT_FAILURE);
    	}
    	e = gfs_pio_close(gf);
    	if (e != NULL) {
    		fprintf(stderr, "gfs_pio_close: %s\n", e);
    		return (EXIT_FAILURE);
    	}
    	e = gfarm_terminate();
    	if (e != NULL) {
    		fprintf(stderr, "gfarm_initialize: %s\n", e);
    		return (EXIT_FAILURE);
    	}
    	return (EXIT_SUCCESS);
    }

## SEE ALSO

gfs_pio_open(3), gfs_pio_getline(3), gfs_pio_gets(3), gfs_pio_readdelim(3)