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add function msgb_printf() to print formatted text into msg buf 

In ASCII string based protocols it a printf() version that prints
directly to the message buffer may be useful.

Add function msgb_printf(), make sure that msg buffer bounderies
are not exceeded. If the end of the tail buffer is hit, return
with an error code.

Change-Id: I15e1af68616309555d0ed9ac5da027c9833d42e3
This commit is contained in:
Philipp Maier 2017-10-10 16:53:21 +02:00 committed by Neels Hofmeyr
parent fcf81b5deb
commit c5b47cc032
4 changed files with 162 additions and 0 deletions
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1
include/osmocom/core/msgb.h
View File

@ -498,5 +498,6 @@ uint8_t *msgb_data(const struct msgb *msg);
void *msgb_talloc_ctx_init(void *root_ctx, unsigned int pool_size);
void msgb_set_talloc_ctx(void *ctx) OSMO_DEPRECATED("Use msgb_talloc_ctx_init() instead");
int msgb_printf(struct msgb *msgb, const char *format, ...);
/*! @} */

48
src/msgb.c
View File

@ -55,6 +55,9 @@
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <stdarg.h>
#include <errno.h>
#include <osmocom/core/msgb.h>
//#include <openbsc/gsm_data.h>
@ -376,4 +379,49 @@ const char *msgb_hexdump(const struct msgb *msg)
return buf;
}
/*! Print a string to the end of message buffer.
* \param[in] msg message buffer
* \returns 0 on success, -EINVAL on error
*
* The resulting string is printed to the msgb without a trailing nul
* character. A nul following the data tail may be written as an implementation
* detail, but a trailing nul is never part of the msgb data in terms of
* msgb_length().
*
* Note: the tailroom must always be one byte longer than the string to be
* written. The msgb is filled only up to tailroom=1. This is an implementation
* detail that allows leaving a nul character behind the valid data.
*
* In case of error, the msgb remains unchanged, though data may have been
* written to the (unused) memory after the tail pointer.
*/
int msgb_printf(struct msgb *msgb, const char *format, ...)
{
va_list args;
int str_len;
int rc = 0;
OSMO_ASSERT(msgb);
OSMO_ASSERT(format);
/* Regardless of what we plan to add to the buffer, we must at least
* be able to store a string terminator (nullstring) */
if (msgb_tailroom(msgb) < 1)
return -EINVAL;
va_start(args, format);
str_len =
vsnprintf((char *)msgb->tail, msgb_tailroom(msgb), format, args);
if (str_len >= msgb_tailroom(msgb) || str_len < 0) {
rc = -EINVAL;
} else
msgb_put(msgb, str_len);
va_end(args);
return rc;
}
/*! @} */

105
tests/msgb/msgb_test.c
View File

@ -277,6 +277,110 @@ static void test_msgb_resize_area()
osmo_set_panic_handler(NULL);
}
static void test_msgb_printf()
{
struct msgb *msg;
struct msgb *msg_ref;
int rc;
int total_len;
msg = msgb_alloc(80, "data");
/* Add normal text: */
printf("Add normal text:\n");
rc = msgb_printf(msg, "|this is a test %i, %s, %16x|", 4711, "testme",
0x4711);
total_len = msgb_length(msg);
printf("#1: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
msg->data);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(msgb_tailroom(msg) == 33);
/* Add normal text: */
rc = msgb_printf(msg, "|some more text|");
total_len = msgb_length(msg);
printf("#2: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
msg->data);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(msgb_tailroom(msg) == 17);
/* Add normal text which will not fit: */
rc = msgb_printf(msg, "|more %i %x %s|", 23, 0xfee,
"text will not fit");
total_len = msgb_length(msg);
printf("#3: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
msg->data);
OSMO_ASSERT(rc == -EINVAL);
/* Check if we got the right amount of characters in the message buffer
* until here, so that we can be sure that the following cornercase
* tests yield plausible results */
OSMO_ASSERT(msgb_tailroom(msg) == 17);
/* Add normal text which just does not fit by one character, this should not
* alter the message buffers tail pointer */
rc = msgb_printf(msg, "|more 123456 ABC|");
total_len = msgb_length(msg);
printf("#4: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
msg->data);
OSMO_ASSERT(rc == -EINVAL);
/* Make sure the tailroom, nor the contained string length did change */
OSMO_ASSERT(msgb_tailroom(msg) == 17);
OSMO_ASSERT(msgb_length(msg) == 63);
/* Add normal text which just fits */
rc = msgb_printf(msg, "|more 123456 AB|");
total_len = msgb_length(msg);
printf("#5: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
msg->data);
OSMO_ASSERT(rc == 0);
/* Make sure that the string in the bufer takes up all available Space.
* Also make sure that the available tailroom has space for one byte,
* which actually holds the string terminator */
OSMO_ASSERT(msgb_tailroom(msg) == 1);
OSMO_ASSERT(msgb_length(msg) == 79);
/* Try to add a nullstring to the already full buffer, this should
* be ok, since we still have one byte tailroom */
rc = msgb_printf(msg, "");
total_len = msgb_length(msg);
printf("#6: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
msg->data);
OSMO_ASSERT(rc == 0);
/* Make sure that we still have the same conditions as before */
OSMO_ASSERT(msgb_tailroom(msg) == 1);
OSMO_ASSERT(msgb_length(msg) == 79);
msgb_free(msg);
/* Test behaviour when a completely full buffer is passed to
* msgb_printf(). We should get rc == -EINVAL and the message
* buffer must not be changed at all */
msg = msgb_alloc(15, "data");
msg_ref = msgb_alloc(msgb_tailroom(msg), "data");
memset(msg->data, 0x41, msgb_tailroom(msg));
memset(msg_ref->data, 0x41, msgb_tailroom(msg_ref));
msgb_put(msg, msgb_tailroom(msg));
msgb_put(msg_ref, msgb_tailroom(msg_ref));
printf("#7: before: %s", msgb_hexdump(msg));
rc = msgb_printf(msg, "ABCDEF");
printf(" after: rc=%i, %s", rc, msgb_hexdump(msg));
if (memcmp(msg->data, msg_ref->data, msgb_length(msg)) == 0)
printf(" ==> ok, no change\n");
else
printf(" ==> error, change detected\n");
OSMO_ASSERT(rc == -EINVAL);
OSMO_ASSERT(msgb_tailroom(msg) == 0);
OSMO_ASSERT(msgb_length(msg) == msgb_length(msg_ref));
msgb_free(msg);
msgb_free(msg_ref);
}
static struct log_info info = {};
int main(int argc, char **argv)
@ -287,6 +391,7 @@ int main(int argc, char **argv)
test_msgb_api_errors();
test_msgb_copy();
test_msgb_resize_area();
test_msgb_printf();
printf("Success.\n");

8
tests/msgb/msgb_test.ok
View File

@ -32,4 +32,12 @@ Testing msgb_resize_area
Original: [L1]> 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 [L2]> 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 [L3]> 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39 3a 3b [L4]> 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
Extended: [L1]> 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 [L2]> 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [L3]> 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39 3a 3b [L4]> 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
Shrinked: [L1]> 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 [L2]> 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [L3]> 28 29 2a 2b 2c 2d 2e 2f 30 31 [L4]> 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
Add normal text:
#1: rc=0, total_len=47, msg->data=|this is a test 4711, testme, 4711|
#2: rc=0, total_len=63, msg->data=|this is a test 4711, testme, 4711||some more text|
#3: rc=-22, total_len=63, msg->data=|this is a test 4711, testme, 4711||some more text||more 23 fee tex
#4: rc=-22, total_len=63, msg->data=|this is a test 4711, testme, 4711||some more text||more 123456 ABC
#5: rc=0, total_len=79, msg->data=|this is a test 4711, testme, 4711||some more text||more 123456 AB|
#6: rc=0, total_len=79, msg->data=|this is a test 4711, testme, 4711||some more text||more 123456 AB|
#7: before: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 after: rc=-22, 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 ==> ok, no change
Success.