chunk: Use dynamically allocated buffer in chunk_from_fd()

When acting on files, we can use fstat() to estimate the buffer size. On
non-file FDs, we dynamically increase an allocated buffer.

Additionally we slightly change the function signature to properly handle
zero-length files and add appropriate unit tests.

src/libstrongswan/tests/suites/test_chunk.c

@@ -17,8 +17,13 @@
 #include "test_suite.h"
 
 #include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
 
 #include <utils/chunk.h>
+#include <threading/thread.h>
 
 /*******************************************************************************
  * utilities
@@ -812,6 +817,79 @@ START_TEST(test_chunk_map)
 }
 END_TEST
 
+/*******************************************************************************
+ * test for chunk_from_fd
+ */
+
+START_TEST(test_chunk_from_fd_file)
+{
+	chunk_t in, contents = chunk_from_chars(0x01,0x02,0x03,0x04,0x05);
+	char *path = "/tmp/strongswan-chunk-fd-test";
+	int fd;
+
+	ck_assert(chunk_write(contents, path, "chunk_fd", 022, TRUE));
+
+	fd = open(path, O_RDONLY);
+	ck_assert(fd != -1);
+
+	ck_assert(chunk_from_fd(fd, &in));
+	close(fd);
+	ck_assert_msg(chunk_equals(in, contents), "%B", &in);
+	unlink(path);
+	free(in.ptr);
+}
+END_TEST
+
+START_TEST(test_chunk_from_fd_skt)
+{
+	chunk_t in, contents = chunk_from_chars(0x01,0x02,0x03,0x04,0x05);
+	int s[2];
+
+	ck_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, s) == 0);
+	ck_assert(write(s[1], contents.ptr, contents.len) == contents.len);
+	close(s[1]);
+	ck_assert_msg(chunk_from_fd(s[0], &in), "%s", strerror(errno));
+	close(s[0]);
+	ck_assert_msg(chunk_equals(in, contents), "%B", &in);
+	free(in.ptr);
+}
+END_TEST
+
+#define FROM_FD_COUNT 8192
+
+void *chunk_from_fd_run(void *data)
+{
+	int i, fd = (uintptr_t)data;
+
+	for (i = 0; i < FROM_FD_COUNT; i++)
+	{
+		ck_assert(write(fd, &i, sizeof(i)) == sizeof(i));
+	}
+	close(fd);
+	return NULL;
+}
+
+START_TEST(test_chunk_from_fd_huge)
+{
+	thread_t *thread;
+	chunk_t in;
+	int s[2], i;
+
+	ck_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, s) == 0);
+
+	thread = thread_create(chunk_from_fd_run, (void*)(uintptr_t)s[1]);
+	ck_assert_msg(chunk_from_fd(s[0], &in), "%s", strerror(errno));
+	ck_assert_int_eq(in.len, FROM_FD_COUNT * sizeof(i));
+	for (i = 0; i < FROM_FD_COUNT; i++)
+	{
+		ck_assert_int_eq(((int*)in.ptr)[i], i);
+	}
+	thread->join(thread);
+	close(s[0]);
+	free(in.ptr);
+}
+END_TEST
+
 /*******************************************************************************
  * printf_hook tests
  */
@@ -933,6 +1011,12 @@ Suite *chunk_suite_create()
 	tcase_add_test(tc, test_chunk_map);
 	suite_add_tcase(s, tc);
 
+	tc = tcase_create("chunk_from_fd");
+	tcase_add_test(tc, test_chunk_from_fd_file);
+	tcase_add_test(tc, test_chunk_from_fd_skt);
+	tcase_add_test(tc, test_chunk_from_fd_huge);
+	suite_add_tcase(s, tc);
+
 	tc = tcase_create("printf_hook");
 	tcase_add_loop_test(tc, test_printf_hook_hash, 0, countof(printf_hook_data));
 	tcase_add_loop_test(tc, test_printf_hook_plus, 0, countof(printf_hook_data));

src/libstrongswan/utils/chunk.c

@@ -247,33 +247,62 @@ bool chunk_write(chunk_t chunk, char *path, char *label, mode_t mask, bool force
 /**
  * Described in header.
  */
-chunk_t chunk_from_fd(int fd)
+bool chunk_from_fd(int fd, chunk_t *out)
 {
-	char buf[8096];
-	char *pos = buf;
-	ssize_t len, total = 0;
+	struct stat sb;
+	char *buf, *tmp;
+	ssize_t len, total = 0, bufsize;
+
+	if (fstat(fd, &sb) == 0 && S_ISREG(sb.st_mode))
+	{
+		bufsize = sb.st_size;
+	}
+	else
+	{
+		bufsize = 256;
+	}
+	buf = malloc(bufsize);
+	if (!buf)
+	{	/* for huge files */
+		return FALSE;
+	}
 
 	while (TRUE)
 	{
-		len = read(fd, pos, buf + sizeof(buf) - pos);
+		len = read(fd, buf + total, bufsize - total);
 		if (len < 0)
 		{
-			DBG1(DBG_LIB, "reading from file descriptor failed: %s",
-				 strerror(errno));
-			return chunk_empty;
+			free(buf);
+			return FALSE;
 		}
 		if (len == 0)
 		{
 			break;
 		}
 		total += len;
-		if (total == sizeof(buf))
+		if (total == bufsize)
 		{
-			DBG1(DBG_LIB, "buffer too small to read from file descriptor");
-			return chunk_empty;
+			bufsize *= 2;
+			tmp = realloc(buf, bufsize);
+			if (!tmp)
+			{
+				free(buf);
+				return FALSE;
+			}
+			buf = tmp;
 		}
 	}
-	return chunk_clone(chunk_create(buf, total));
+	if (total == 0)
+	{
+		free(buf);
+		buf = NULL;
+	}
+	else if (total < bufsize)
+	{
+		buf = realloc(buf, total);
+	}
+	*out = chunk_create(buf, total);
+	return TRUE;
 }
 
 /**

src/libstrongswan/utils/chunk.h

@@ -102,10 +102,13 @@ bool chunk_write(chunk_t chunk, char *path, char *label, mode_t mask, bool force
 /**
  * Store data read from FD into a chunk
  *
+ * On error, errno is set appropriately.
+ *
  * @param fd			file descriptor to read from
- * @return				chunk or chunk_empty on failure
+ * @param chunk			chunk receiving allocated buffer
+ * @return				TRUE if successful, FALSE on failure
  */
-chunk_t chunk_from_fd(int fd);
+bool chunk_from_fd(int fd, chunk_t *chunk);
 
 /**
  * mmap() a file to a chunk

src/pki/commands/issue.c

@@ -14,6 +14,7 @@
  */
 
 #include <time.h>
+#include <errno.h>
 
 #include "pki.h"
 
@@ -382,7 +383,12 @@ static int issue()
 		{
 			chunk_t chunk;
 
-			chunk = chunk_from_fd(0);
+			if (!chunk_from_fd(0, &chunk))
+			{
+				fprintf(stderr, "%s: ", strerror(errno));
+				error = "reading certificate request failed";
+				goto end;
+			}
 			cert_req = lib->creds->create(lib->creds, CRED_CERTIFICATE,
 										  CERT_PKCS10_REQUEST,
 										  BUILD_BLOB, chunk, BUILD_END);
@@ -425,7 +431,12 @@ static int issue()
 		{
 			chunk_t chunk;
 
-			chunk = chunk_from_fd(0);
+			if (!chunk_from_fd(0, &chunk))
+			{
+				fprintf(stderr, "%s: ", strerror(errno));
+				error = "reading public key failed";
+				goto end;
+			}
 			public = lib->creds->create(lib->creds, CRED_PUBLIC_KEY, KEY_ANY,
 										 BUILD_BLOB, chunk, BUILD_END);
 			free(chunk.ptr);
@@ -562,4 +573,3 @@ static void __attribute__ ((constructor))reg()
 		}
 	});
 }
-

src/pki/commands/keyid.c

@@ -13,6 +13,8 @@
  * for more details.
  */
 
+#include <errno.h>
+
 #include "pki.h"
 
 #include <credentials/certificates/certificate.h>
@@ -89,7 +91,11 @@ static int keyid()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading input failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cred = lib->creds->create(lib->creds, type, subtype,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);
@@ -165,4 +171,3 @@ static void __attribute__ ((constructor))reg()
 		}
 	});
 }
-

src/pki/commands/print.c

@@ -22,6 +22,7 @@
 #include <selectors/traffic_selector.h>
 
 #include <time.h>
+#include <errno.h>
 
 /**
  * Print public key information
@@ -510,7 +511,11 @@ static int print()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading input failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cred = lib->creds->create(lib->creds, type, subtype,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);

src/pki/commands/pub.c

@@ -13,6 +13,8 @@
  * for more details.
  */
 
+#include <errno.h>
+
 #include "pki.h"
 
 #include <credentials/certificates/certificate.h>
@@ -108,7 +110,11 @@ static int pub()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading input failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cred = lib->creds->create(lib->creds, type, subtype,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);
@@ -186,4 +192,3 @@ static void __attribute__ ((constructor))reg()
 		}
 	});
 }
-

src/pki/commands/req.c

@@ -16,6 +16,7 @@
  */
 
 #include <time.h>
+#include <errno.h>
 
 #include "pki.h"
 
@@ -118,7 +119,11 @@ static int req()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading private key failed: %s\n", strerror(errno));
+			return 1;
+		}
 		private = lib->creds->create(lib->creds, CRED_PRIVATE_KEY, type,
 									 BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);

src/pki/commands/self.c

@@ -14,6 +14,7 @@
  */
 
 #include <time.h>
+#include <errno.h>
 
 #include "pki.h"
 
@@ -273,7 +274,12 @@ static int self()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "%s: ", strerror(errno));
+			error = "reading private key failed";
+			goto end;
+		}
 		private = lib->creds->create(lib->creds, CRED_PRIVATE_KEY, type,
 									 BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);

src/pki/commands/verify.c

@@ -13,6 +13,8 @@
  * for more details.
  */
 
+#include <errno.h>
+
 #include "pki.h"
 
 #include <credentials/certificates/certificate.h>
@@ -57,7 +59,11 @@ static int verify()
 	{
 		chunk_t chunk;
 
-		chunk = chunk_from_fd(0);
+		if (!chunk_from_fd(0, &chunk))
+		{
+			fprintf(stderr, "reading certificate failed: %s\n", strerror(errno));
+			return 1;
+		}
 		cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509,
 								  BUILD_BLOB, chunk, BUILD_END);
 		free(chunk.ptr);