usr/kinit/readfile.c

/*
 * Read the entire contents of a file into malloc'd storage.  This
 * is mostly useful for things like /proc files where we can't just
 * fstat() to get the length and then mmap().
 *
 * Returns the number of bytes read, or -1 on error.
 */

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/stat.h>

#include "kinit.h"

ssize_t freadfile(FILE *f, char **pp)
{
	size_t bs;		/* Decent starting point... */
	size_t bf;		/* Bytes free */
	size_t bu = 0;		/* Bytes used */
	char *buffer, *nb;
	size_t rv;
	int old_errno = errno;

	bs = BUFSIZ;		/* A guess as good as any */
	bf = bs;
	buffer = malloc(bs);

	if (!buffer)
		return -1;

	for (;;) {
		errno = 0;

		while (bf && (rv = _fread(buffer + bu, bf, f))) {
			bu += rv;
			bf -= rv;
		}

		if (errno && errno != EINTR && errno != EAGAIN) {
			/* error */
			free(buffer);
			return -1;
		}

		if (bf) {
			/* Hit EOF, no error */

			/* Try to free superfluous memory */
			if ((nb = realloc(buffer, bu + 1)))
				buffer = nb;

			/* Null-terminate result for good measure */
			buffer[bu] = '\0';

			*pp = buffer;
			errno = old_errno;
			return bu;
		}

		/* Double the size of the buffer */
		bf += bs;
		bs += bs;
		if (!(nb = realloc(buffer, bs))) {
			/* out of memory error */
			free(buffer);
			return -1;
		}
		buffer = nb;
	}
}

ssize_t readfile(const char *filename, char **pp)
{
	FILE *f = fopen(filename, "r");
	ssize_t rv;

	if (!f)
		return -1;

	rv = freadfile(f, pp);

	fclose(f);

	return rv;
}
1	/*
2	* Read the entire contents of a file into malloc'd storage. This
3	* is mostly useful for things like /proc files where we can't just
4	* fstat() to get the length and then mmap().
5	*
6	* Returns the number of bytes read, or -1 on error.
7	*/
8
9	#include <stdlib.h>
10	#include <stdio.h>
11	#include <errno.h>
12	#include <sys/stat.h>
13
14	#include "kinit.h"
15
16	ssize_t freadfile(FILE f, char *pp)
17	{
18	size_t bs; /* Decent starting point... */
19	size_t bf; /* Bytes free */
20	size_t bu = 0; /* Bytes used */
21	char buffer, nb;
22	size_t rv;
23	int old_errno = errno;
24
25	bs = BUFSIZ; /* A guess as good as any */
26	bf = bs;
27	buffer = malloc(bs);
28
29	if (!buffer)
30	return -1;
31
32	for (;;) {
33	errno = 0;
34
35	while (bf && (rv = _fread(buffer + bu, bf, f))) {
36	bu += rv;
37	bf -= rv;
38	}
39
40	if (errno && errno != EINTR && errno != EAGAIN) {
41	/* error */
42	free(buffer);
43	return -1;
44	}
45
46	if (bf) {
47	/* Hit EOF, no error */
48
49	/* Try to free superfluous memory */
50	if ((nb = realloc(buffer, bu + 1)))
51	buffer = nb;
52
53	/* Null-terminate result for good measure */
54	buffer[bu] = '\0';
55
56	*pp = buffer;
57	errno = old_errno;
58	return bu;
59	}
60
61	/* Double the size of the buffer */
62	bf += bs;
63	bs += bs;
64	if (!(nb = realloc(buffer, bs))) {
65	/* out of memory error */
66	free(buffer);
67	return -1;
68	}
69	buffer = nb;
70	}
71	}
72
73	ssize_t readfile(const char filename, char *pp)
74	{
75	FILE *f = fopen(filename, "r");
76	ssize_t rv;
77
78	if (!f)
79	return -1;
80
81	rv = freadfile(f, pp);
82
83	fclose(f);
84
85	return rv;
86	}