Author: gahr (ports committer)
Date: Thu Jan 31 16:39:50 2013
New Revision: 246148
URL: http://svnweb.freebsd.org/changeset/base/246148
Log:
- Remove underscores from the internal structure name, as it doesn't collide
with the user's namespace.
- Correct size and position variables type from long to size_t.
- Do not set errno to ENOMEM on malloc failure, as malloc already does so.
- Implement the concept of "buffer data length", which mandates what SEEK_END
refers to and the allowed extent for a read.
- Use NULL as read-callback if the buffer is opened in write-only mode.
Conversely, use NULL as write-callback when opened in read-only mode.
- Implement the handling of the ``b'' character in the mode argument. A binary
buffer differs from a text buffer (default mode if ``b'' is omitted) in that
NULL bytes are never appended to writes and that the "buffer data length"
equals to the size of the buffer.
- Remove shall from the man page. Use indicative instead. Also, specify that
the ``b'' flag does not conform with POSIX but is supported by glibc.
- Update the regression test so that the ``b'' functionality and the "buffer
data length" concepts are tested.
- Minor style(9) corrections.
Suggested by: jilles
Reviewed by: cognet
Approved by: cognet
Modified:
head/lib/libc/stdio/fmemopen.c
head/lib/libc/stdio/fopen.3
head/tools/regression/lib/libc/stdio/test-fmemopen.c
Modified: head/lib/libc/stdio/fmemopen.c
==============================================================================
--- head/lib/libc/stdio/fmemopen.c Thu Jan 31 16:04:40 2013
(r246147)
+++ head/lib/libc/stdio/fmemopen.c Thu Jan 31 16:39:50 2013
(r246148)
@@ -26,17 +26,21 @@ SUCH DAMAGE.
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
+#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
+#include "local.h"
-struct __fmemopen_cookie
+struct fmemopen_cookie
{
- char *buf; /* pointer to the memory region */
- char own; /* did we allocate the buffer ourselves? */
- long len; /* buffer length in bytes */
- long off; /* current offset into the buffer */
+ char *buf; /* pointer to the memory region */
+ char own; /* did we allocate the buffer ourselves? */
+ char bin; /* is this a binary buffer? */
+ size_t size; /* buffer length in bytes */
+ size_t len; /* data length in bytes */
+ size_t off; /* current offset into the buffer */
};
static int fmemopen_read (void *cookie, char *buf, int nbytes);
@@ -47,33 +51,95 @@ static int fmemopen_close (void *cookie)
FILE *
fmemopen (void * __restrict buf, size_t size, const char * __restrict mode)
{
- /* allocate cookie */
- struct __fmemopen_cookie *ck = malloc (sizeof (struct
__fmemopen_cookie));
+ struct fmemopen_cookie *ck;
+ FILE *f;
+ int flags, rc;
+
+ /*
+ * Retrieve the flags as used by open(2) from the mode argument, and
+ * validate them.
+ * */
+ rc = __sflags (mode, &flags);
+ if (rc == 0) {
+ errno = EINVAL;
+ return (NULL);
+ }
+
+ /*
+ * There's no point in requiring an automatically allocated buffer
+ * in write-only mode.
+ */
+ if (!(flags & O_RDWR) && buf == NULL) {
+ errno = EINVAL;
+ return (NULL);
+ }
+
+ /* Allocate a cookie. */
+ ck = malloc (sizeof (struct fmemopen_cookie));
if (ck == NULL) {
- errno = ENOMEM;
return (NULL);
}
- ck->off = 0;
- ck->len = size;
+ ck->off = 0;
+ ck->size = size;
- /* do we have to allocate the buffer ourselves? */
+ /* Check whether we have to allocate the buffer ourselves. */
ck->own = ((ck->buf = buf) == NULL);
if (ck->own) {
ck->buf = malloc (size);
if (ck->buf == NULL) {
free (ck);
- errno = ENOMEM;
return (NULL);
}
+ }
+
+ /*
+ * POSIX distinguishes between w+ and r+, in that w+ is supposed to
+ * truncate the buffer.
+ */
+ if (ck->own || mode[0] == 'w') {
ck->buf[0] = '\0';
}
- if (mode[0] == 'a')
- ck->off = strnlen(ck->buf, ck->len);
+ /* Check for binary mode. */
+ ck->bin = strchr(mode, 'b') != NULL;
- /* actuall wrapper */
- FILE *f = funopen ((void *)ck, fmemopen_read, fmemopen_write,
+ /*
+ * The size of the current buffer contents is set depending on the
+ * mode:
+ *
+ * for append (text-mode), the position of the first NULL byte, or the
+ * size of the buffer if none is found
+ *
+ * for append (binary-mode), the size of the buffer
+ *
+ * for read, the size of the buffer
+ *
+ * for write, 0
+ */
+ switch (mode[0]) {
+ case 'a':
+ if (ck->bin) {
+ /*
+ * This isn't useful, since the buffer isn't
+ * allowed to grow.
+ */
+ ck->off = ck->len = size;
+ } else
+ ck->off = ck->len = strnlen(ck->buf, ck->size);
+ break;
+ case 'r':
+ ck->len = size;
+ break;
+ case 'w':
+ ck->len = 0;
+ break;
+ }
+
+ /* Actuall wrapper. */
+ f = funopen ((void *)ck,
+ flags & O_WRONLY ? NULL : fmemopen_read,
+ flags & O_RDONLY ? NULL : fmemopen_write,
fmemopen_seek, fmemopen_close);
if (f == NULL) {
@@ -83,8 +149,10 @@ fmemopen (void * __restrict buf, size_t
return (NULL);
}
- /* turn off buffering, so a write past the end of the buffer
- * correctly returns a short object count */
+ /*
+ * Turn off buffering, so a write past the end of the buffer
+ * correctly returns a short object count.
+ */
setvbuf (f, (char *) NULL, _IONBF, 0);
return (f);
@@ -93,7 +161,7 @@ fmemopen (void * __restrict buf, size_t
static int
fmemopen_read (void *cookie, char *buf, int nbytes)
{
- struct __fmemopen_cookie *ck = cookie;
+ struct fmemopen_cookie *ck = cookie;
if (nbytes > ck->len - ck->off)
nbytes = ck->len - ck->off;
@@ -111,10 +179,10 @@ fmemopen_read (void *cookie, char *buf,
static int
fmemopen_write (void *cookie, const char *buf, int nbytes)
{
- struct __fmemopen_cookie *ck = cookie;
+ struct fmemopen_cookie *ck = cookie;
- if (nbytes > ck->len - ck->off)
- nbytes = ck->len - ck->off;
+ if (nbytes > ck->size - ck->off)
+ nbytes = ck->size - ck->off;
if (nbytes == 0)
return (0);
@@ -123,7 +191,16 @@ fmemopen_write (void *cookie, const char
ck->off += nbytes;
- if (ck->off < ck->len && ck->buf[ck->off - 1] != '\0')
+ if (ck->off > ck->len)
+ ck->len = ck->off;
+
+ /*
+ * We append a NULL byte if all these conditions are met:
+ * - the buffer is not binary
+ * - the buffer is not full
+ * - the data just written doesn't already end with a NULL byte
+ */
+ if (!ck->bin && ck->off < ck->size && ck->buf[ck->off - 1] != '\0')
ck->buf[ck->off] = '\0';
return (nbytes);
@@ -132,12 +209,12 @@ fmemopen_write (void *cookie, const char
static fpos_t
fmemopen_seek (void *cookie, fpos_t offset, int whence)
{
- struct __fmemopen_cookie *ck = cookie;
+ struct fmemopen_cookie *ck = cookie;
switch (whence) {
case SEEK_SET:
- if (offset > ck->len) {
+ if (offset > ck->size) {
errno = EINVAL;
return (-1);
}
@@ -145,7 +222,7 @@ fmemopen_seek (void *cookie, fpos_t offs
break;
case SEEK_CUR:
- if (ck->off + offset > ck->len) {
+ if (ck->off + offset > ck->size) {
errno = EINVAL;
return (-1);
}
@@ -171,7 +248,7 @@ fmemopen_seek (void *cookie, fpos_t offs
static int
fmemopen_close (void *cookie)
{
- struct __fmemopen_cookie *ck = cookie;
+ struct fmemopen_cookie *ck = cookie;
if (ck->own)
free (ck->buf);
Modified: head/lib/libc/stdio/fopen.3
==============================================================================
--- head/lib/libc/stdio/fopen.3 Thu Jan 31 16:04:40 2013 (r246147)
+++ head/lib/libc/stdio/fopen.3 Thu Jan 31 16:39:50 2013 (r246148)
@@ -118,7 +118,9 @@ after either the
or the first letter.
This is strictly for compatibility with
.St -isoC
-and has no effect; the ``b'' is ignored.
+and has effect only for
+.Fn fmemopen
+; otherwise the ``b'' is ignored.
.Pp
Any created files will have mode
.Do Dv S_IRUSR
@@ -216,7 +218,7 @@ and
arguments with a stream.
The
.Fa buf
-argument shall be either a null pointer or point to a buffer that
+argument is either a null pointer or point to a buffer that
is at least
.Fa size
bytes long.
@@ -224,10 +226,15 @@ If a null pointer is specified as the
.Fa buf
argument,
.Fn fmemopen
-shall allocate
+allocates
.Fa size
-bytes of memory. This buffer shall be automatically freed when the
-stream is closed.
+bytes of memory. This buffer is automatically freed when the
+stream is closed. Buffers can be opened in text-mode (default) or binary-mode
+(if ``b'' is present in the second or third position of the
+.Fa mode
+argument). Buffers opened in text-mode make sure that writes are terminated
with
+a NULL byte, if the last write hasn't filled up the whole buffer. Buffers
+opened in binary-mode never append a NULL byte.
.Sh RETURN VALUES
Upon successful completion
.Fn fopen ,
@@ -327,3 +334,5 @@ The
function
conforms to
.St -p1003.1-2008 .
+The ``b'' mode does not conform to any standard
+but is also supported by glibc.
Modified: head/tools/regression/lib/libc/stdio/test-fmemopen.c
==============================================================================
--- head/tools/regression/lib/libc/stdio/test-fmemopen.c Thu Jan 31
16:04:40 2013 (r246147)
+++ head/tools/regression/lib/libc/stdio/test-fmemopen.c Thu Jan 31
16:39:50 2013 (r246148)
@@ -41,7 +41,7 @@ void
test_preexisting ()
{
/*
- * use a pre-existing buffer
+ * Use a pre-existing buffer.
*/
char buf[512];
@@ -53,48 +53,52 @@ test_preexisting ()
size_t nofw, nofr;
int rc;
- /* open a FILE * using fmemopen */
- fp = fmemopen (buf, sizeof buf, "w");
+ /* Open a FILE * using fmemopen. */
+ fp = fmemopen (buf, sizeof(buf), "w");
assert (fp != NULL);
- /* write to the buffer */
- nofw = fwrite (str, 1, sizeof str, fp);
- assert (nofw == sizeof str);
+ /* Write to the buffer. */
+ nofw = fwrite (str, 1, sizeof(str), fp);
+ assert (nofw == sizeof(str));
- /* close the FILE * */
+ /* Close the FILE *. */
rc = fclose (fp);
assert (rc == 0);
- /* re-open the FILE * to read back the data */
- fp = fmemopen (buf, sizeof buf, "r");
+ /* Re-open the FILE * to read back the data. */
+ fp = fmemopen (buf, sizeof(buf), "r");
assert (fp != NULL);
- /* read from the buffer */
- bzero (buf2, sizeof buf2);
- nofr = fread (buf2, 1, sizeof buf2, fp);
- assert (nofr == sizeof buf2);
+ /* Read from the buffer. */
+ bzero (buf2, sizeof(buf2));
+ nofr = fread (buf2, 1, sizeof(buf2), fp);
+ assert (nofr == sizeof(buf2));
- /* since a write on a FILE * retrieved by fmemopen
+ /*
+ * Since a write on a FILE * retrieved by fmemopen
* will add a '\0' (if there's space), we can check
- * the strings for equality */
+ * the strings for equality.
+ */
assert (strcmp(str, buf2) == 0);
- /* close the FILE * */
+ /* Close the FILE *. */
rc = fclose (fp);
assert (rc == 0);
- /* now open a FILE * on the first 4 bytes of the string */
+ /* Now open a FILE * on the first 4 bytes of the string. */
fp = fmemopen (str, 4, "w");
assert (fp != NULL);
- /* try to write more bytes than we shoud, we'll get a short count (4) */
- nofw = fwrite (str2, 1, sizeof str2, fp);
+ /*
+ * Try to write more bytes than we shoud, we'll get a short count (4).
+ */
+ nofw = fwrite (str2, 1, sizeof(str2), fp);
assert (nofw == 4);
- /* close the FILE * */
+ /* Close the FILE *. */
rc = fclose (fp);
- /* check that the string was not modified after the first 4 bytes */
+ /* Check that the string was not modified after the first 4 bytes. */
assert (strcmp (str, str3) == 0);
}
@@ -102,7 +106,7 @@ void
test_autoalloc ()
{
/*
- * let fmemopen allocate the buffer
+ * Let fmemopen allocate the buffer.
*/
char str[] = "A quick test";
@@ -111,8 +115,8 @@ test_autoalloc ()
size_t nofw, nofr, i;
int rc;
- /* open a FILE * using fmemopen */
- fp = fmemopen (NULL, 512, "w");
+ /* Open a FILE * using fmemopen. */
+ fp = fmemopen (NULL, 512, "w+");
assert (fp != NULL);
/* fill the buffer */
@@ -121,15 +125,118 @@ test_autoalloc ()
assert (nofw == 1);
}
- /* get the current position into the stream */
+ /* Get the current position into the stream. */
pos = ftell (fp);
assert (pos == 512);
- /* try to write past the end, we should get a short object count (0) */
+ /*
+ * Try to write past the end, we should get a short object count (0)
+ */
nofw = fwrite ("a", 1, 1, fp);
assert (nofw == 0);
- /* close the FILE * */
+ /* Close the FILE *. */
+ rc = fclose (fp);
+ assert (rc == 0);
+}
+
+void
+test_data_length ()
+{
+ /*
+ * Here we test that a read operation doesn't go past the end of the
+ * data actually written, and that a SEEK_END seeks from the end of the
+ * data, not of the whole buffer.
+ */
+ FILE *fp;
+ char buf[512] = {'\0'};
+ char str[] = "Test data length. ";
+ char str2[] = "Do we have two sentences?";
+ char str3[sizeof(str) + sizeof(str2) -1];
+ long pos;
+ size_t nofw, nofr;
+ int rc;
+
+ /* Open a FILE * for updating our buffer. */
+ fp = fmemopen (buf, sizeof(buf), "w+");
+ assert (fp != NULL);
+
+ /* Write our string into the buffer. */
+ nofw = fwrite (str, 1, sizeof(str), fp);
+ assert (nofw == sizeof(str));
+
+ /*
+ * Now seek to the end and check that ftell
+ * gives us sizeof(str).
+ */
+ rc = fseek (fp, 0, SEEK_END);
+ assert (rc == 0);
+ pos = ftell (fp);
+ assert (pos == sizeof(str));
+
+ /* Close the FILE *. */
+ rc = fclose (fp);
+ assert (rc == 0);
+
+ /* Reopen the buffer for appending. */
+ fp = fmemopen (buf, sizeof(buf), "a+");
+ assert (fp != NULL);
+
+ /* We should now be writing after the first string. */
+ nofw = fwrite (str2, 1, sizeof(str2), fp);
+ assert (nofw == sizeof(str2));
+
+ /* Rewind the FILE *. */
+ rc = fseek (fp, 0, SEEK_SET);
+ assert (rc == 0);
+
+ /* Make sure we're at the beginning. */
+ pos = ftell (fp);
+ assert (pos == 0);
+
+ /* Read the whole buffer. */
+ nofr = fread (str3, 1, sizeof(buf), fp);
+ assert (nofr == sizeof(str3));
+
+ /* Make sure the two strings are there. */
+ assert (strncmp (str3, str, sizeof(str) - 1) == 0);
+ assert (strncmp (str3 + sizeof(str) - 1, str2, sizeof(str2)) == 0);
+
+ /* Close the FILE *. */
+ rc = fclose (fp);
+ assert (rc == 0);
+}
+
+void
+test_binary ()
+{
+ /*
+ * Make sure that NULL bytes are never appended when opening a buffer
+ * in binary mode.
+ */
+
+ FILE *fp;
+ char buf[20];
+ char str[] = "Test";
+ size_t nofw;
+ int rc, i;
+
+ /* Pre-fill the buffer. */
+ memset (buf, 'A', sizeof(buf));
+
+ /* Open a FILE * in binary mode. */
+ fp = fmemopen (buf, sizeof(buf), "w+b");
+ assert (fp != NULL);
+
+ /* Write some data into it. */
+ nofw = fwrite (str, 1, strlen(str), fp);
+ assert (nofw == strlen(str));
+
+ /* Make sure that the buffer doesn't contain any NULL bytes. */
+ for (i = 0; i < sizeof(buf); i++)
+ assert (buf[i] != '\0');
+
+ /* Close the FILE *. */
rc = fclose (fp);
assert (rc == 0);
}
@@ -139,5 +246,7 @@ main (void)
{
test_autoalloc ();
test_preexisting ();
+ test_data_length ();
+ test_binary ();
return (0);
}
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