[PATCH] libosmocore[master]: add function msgb_printf() to print formatted text into msg buf

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dexter gerrit-no-reply at lists.osmocom.org
Thu Oct 12 10:09:16 UTC 2017


Hello Max, Jenkins Builder,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/4200

to look at the new patch set (#3).

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
---
M include/osmocom/core/msgb.h
M src/msgb.c
M tests/msgb/msgb_test.c
M tests/msgb/msgb_test.ok
4 files changed, 136 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/00/4200/3

diff --git a/include/osmocom/core/msgb.h b/include/osmocom/core/msgb.h
index 91b7ec7..9c3ccf0 100644
--- a/include/osmocom/core/msgb.h
+++ b/include/osmocom/core/msgb.h
@@ -498,5 +498,6 @@
 
 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, ...);
 
 /*! @} */
diff --git a/src/msgb.c b/src/msgb.c
index 2e9f4a2..46287b5 100644
--- a/src/msgb.c
+++ b/src/msgb.c
@@ -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 +379,56 @@
 	return buf;
 }
 
+
+/*! Print a string to the end of message buffer
+ * \param[in] msg message buffer
+ * \returns 0 on success, -EINVAL on error
+ *
+ * If less then 1 character of tailroom is left over, the message buffer
+ * will not be changed at all.
+ *
+ * In case of error, the message buffer may be left with invalid data
+ * appended. However, if an error is detected the tail pointer will not
+ * be moved and a terminating \0 is written to the tail position, this
+ * will clamp off the truncated string. The message buffer is immediately
+ * ready for a second attempt (with less data).
+ *
+ * In case of success the resulting string is written to the memory where
+ * the tail pointer points to. The tail pointer is then moved to the end
+ * of the string so that it points exactly to the location of the string
+ * terminator.
+ *
+ * When msgb_printf() is called multiple times with different data, the
+ * result will be a single, concatenated string.
+ */
+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) {
+		*msgb->tail = '\0';
+		rc = -EINVAL;
+	} else
+		msgb_put(msgb, str_len);
+
+	va_end(args);
+	return rc;
+}
+
+
 /*! @} */
diff --git a/tests/msgb/msgb_test.c b/tests/msgb/msgb_test.c
index ac10382..edc2412 100644
--- a/tests/msgb/msgb_test.c
+++ b/tests/msgb/msgb_test.c
@@ -276,6 +276,78 @@
 
 	osmo_set_panic_handler(NULL);
 }
+static void test_msgb_printf()
+{
+	struct msgb *msg = msgb_alloc(80, "data");
+	int rc;
+	int total_len;
+
+	/* Add normal text: */
+	printf("Add normal text:\n");
+	rc = msgb_printf(msg, "|this is a test %i, %s, %16x|", 4711, "testme",
+			 0x4711);
+	total_len = strlen((char *)msg->data);
+	printf("#1: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
+	       msg->data);
+	OSMO_ASSERT(rc == 0);
+
+	/* Add normal text: */
+	rc = msgb_printf(msg, "|some more text|");
+	total_len = strlen((char *)msg->data);
+	printf("#2: rc=%i, total_len=%i, msg->data=%s\n", rc, total_len,
+	       msg->data);
+	OSMO_ASSERT(rc == 0);
+
+	/* Add normal text which will not fit: */
+	rc = msgb_printf(msg, "|more %i %x %s|", 23, 0xfee,
+			 "text will not fit");
+	total_len = strlen((char *)msg->data);
+	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 = strlen((char *)msg->data);
+	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(total_len == 63);
+
+	/* Add normal text which just fits */
+	rc = msgb_printf(msg, "|more 123456 AB|");
+	total_len = strlen((char *)msg->data);
+	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
+	 * 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(total_len == 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 = strlen((char *)msg->data);
+	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(total_len == 79);
+}
 
 static struct log_info info = {};
 
@@ -287,6 +359,7 @@
 	test_msgb_api_errors();
 	test_msgb_copy();
 	test_msgb_resize_area();
+	test_msgb_printf();
 
 	printf("Success.\n");
 
diff --git a/tests/msgb/msgb_test.ok b/tests/msgb/msgb_test.ok
index 6603fe7..3638515 100644
--- a/tests/msgb/msgb_test.ok
+++ b/tests/msgb/msgb_test.ok
@@ -32,4 +32,11 @@
 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|
+#4: rc=-22, total_len=63, msg->data=|this is a test 4711, testme,             4711||some more text|
+#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|
 Success.

-- 
To view, visit https://gerrit.osmocom.org/4200
To unsubscribe, visit https://gerrit.osmocom.org/settings

Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I15e1af68616309555d0ed9ac5da027c9833d42e3
Gerrit-PatchSet: 3
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: dexter <pmaier at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: Max <msuraev at sysmocom.de>



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