Add lseek

Signed-off-by: Mattias Andrée <maandree@kth.se>

6 files changed, 182 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 9ce5639..a9812c1 100644
--- a/Makefile
+++ b/Makefile
@@ -21,9 +21,11 @@ OBJ =\
 	abs.o\
 	calloc.o\
 	chdir.o\
+	check_kernel_version.o\
 	imaxabs.o\
 	labs.o\
 	llabs.o\
+	lseek.o\
 	malloc.o\
 	pipe.o\
 	putenv.o\
diff --git a/check_kernel_version.c b/check_kernel_version.c
new file mode 100644
index 0000000..ef5dd88
--- /dev/null
+++ b/check_kernel_version.c
@@ -0,0 +1,45 @@
+/* See LICENSE file for copyright and license details. */
+#include "internal.h"
+
+
+int
+liberror_libc_check_kernel_version(long int major, long int minor, long int patch)
+{
+#if defined(__linux__)
+
+	struct utsname name;
+	long int kmajor;
+	long int kminor;
+	long int kpatch;
+	char *p;
+	int r;
+
+	r = uname(&name);
+	if (r < 0)
+		return -1;
+
+	errno = 0;
+	p = name.release;
+	if (!isdigit(*p))
+		return -1;
+	kmajor = strtol(p, &p, 10);
+	if (kmajor < 0 || errno || *p != '.')
+		return -1;
+	kminor = strtol(&p[1], &p, 10);
+	if (kminor < 0 || errno)
+		return -1;
+	if (*p != '.') {
+		kpatch = 0;
+	} else {
+		kpatch = strtol(&p[1], &p, 10);
+		if (kpatch < 0 || errno)
+			return -1;
+	}
+
+	return kmajor != major ? kmajor > major :
+	       kminor != minor ? kminor > minor : kpatch >= patch;
+
+#else
+# error Unsupported kernel
+#endif
+}
diff --git a/config.mk b/config.mk
index 9171a69..c9a4302 100644
--- a/config.mk
+++ b/config.mk
@@ -1,6 +1,6 @@
 PREFIX    = /usr
 MANPREFIX = $(PREFIX)/share/man
 
-CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700
+CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64
 CFLAGS   = -std=c99 -Wall -pedantic
 LDFLAGS  = -s -lerror
diff --git a/internal.h b/internal.h
index 9bc9a26..2605d21 100644
--- a/internal.h
+++ b/internal.h
@@ -3,6 +3,8 @@
 
 #include <netinet/in.h>
 #include <sys/socket.h>
+#include <sys/utsname.h>
+#include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
@@ -22,5 +24,5 @@
 
 #define HIDDEN GCC_ATTRIBUTES(__visibility__("hidden"))
 
-
 HIDDEN void liberror_libc_set_error_one_file(const char *, const char *, const char *, int, const char *);
+HIDDEN int liberror_libc_check_kernel_version(long int, long int, long int);
diff --git a/liberror-libc.h b/liberror-libc.h
index 3ca2b67..ffdc127 100644
--- a/liberror-libc.h
+++ b/liberror-libc.h
@@ -8,6 +8,11 @@
 
 
 #define LIBERROR_LIBC_ERRROR_SHORT_READ -1
+#define LIBERROR_LIBC_ERRROR_SHORT_SEEK -2
+
+
+typedef int64_t _liberror_off_t;
+typedef uint64_t _liberror_uoff_t;
 
 
 int liberror_abs(int);
@@ -23,6 +28,11 @@ long int liberror_labs(long int);
 void liberror_labs_failed(long int);
 long long int liberror_llabs(long long int);
 void liberror_llabs_failed(long long int);
+_liberror_off_t liberror_lseek(int, _liberror_off_t, int, const char *);
+_liberror_off_t liberror_lseek_require(int, _liberror_off_t, int, _liberror_uoff_t min, _liberror_uoff_t max, const char *);
+void liberror_lseek_failed(int, _liberror_off_t, int, const char *);
+void liberror_lseek_short(int, _liberror_off_t, int, _liberror_uoff_t min, _liberror_uoff_t max,
+                          _liberror_off_t returned, const char *);
 void *liberror_malloc(size_t);
 void liberror_malloc_failed(size_t);
 int liberror_pipe(int[2]);
diff --git a/lseek.c b/lseek.c
new file mode 100644
index 0000000..7b1dc90
--- /dev/null
+++ b/lseek.c
@@ -0,0 +1,121 @@
+/* See LICENSE file for copyright and license details. */
+#include "internal.h"
+
+
+void
+liberror_lseek_failed(int fd, _liberror_off_t offset, int whence, const char *fname)
+{
+	const char *desc;
+	int saved_errno = errno;
+	switch (saved_errno) {
+	case EBADF:
+		if (fd < 0)
+			desc = "Negative file descriptor number specified";
+		else
+			desc = "Unassigned file descriptor number specified";
+		break;
+	case ESPIPE:
+		desc = "Unseekable file type (e.g. pipe, socket, or FIFO)";
+		break;
+	case EOVERFLOW:
+		desc = "The resulting offset cannot be represented in an off_t; "
+		       "consider compiling with _FILE_OFFSET_BITS=64";
+		break;
+	case EINVAL:
+		if (whence == SEEK_SET || whence == SEEK_END || whence == SEEK_CUR) {
+			if (offset < 0)
+				desc = "Attempted to seek to a position before the beginning of the file";
+			else if (offset > 0)
+				desc = "Attempted to seek beyond the end of the device";
+			else if (whence == SEEK_SET)
+				desc = "Failed, for unknown reason, to seek to the beginning of the file";
+			else if (whence == SEEK_END)
+				desc = "Failed, for unknown reason, to seek to the end of the device";
+			else
+				desc = "Failed, for unknown reason, to look up current file offset";
+		} else {
+			desc = "Unsupported seek mode";
+			if (whence == SEEK_DATA || whence == SEEK_HOLE) {
+#if defined(__linux__)
+				if (!liberror_libc_check_kernel_version(3, 1, 0))
+					desc = "Unsupported seek mode; requires Linux 3.1 or newer";
+#else
+# error Unsupported kernel
+#endif
+		}
+		}
+		break;
+	case ENXIO:
+		if (whence == SEEK_DATA) {
+			if (offset < 0) {
+				desc = "Attempted seek for data beginning at an offset before the beginning of the file";
+			} else {
+				desc = "Seeking for data from a hold at the end of the file, or at or after the end of the file";
+			}
+		} else if (whence == SEEK_HOLE) {
+			if (offset < 0) {
+				desc = "Attempted seek for a hole beginning at an offset before the beginning of the file";
+			} else {
+				desc = "Attempted seek for a hole from the end of the file, or after it's end";
+			}
+		}
+		break;
+	default:
+		desc = "";
+		break;
+	}
+	liberror_libc_set_error_one_file(desc, "sockatmark", "Seekable file", fd, fname);
+	errno = saved_errno;
+}
+
+
+void
+liberror_lseek_short(int fd, _liberror_off_t offset, int whence, _liberror_uoff_t min,
+                     _liberror_uoff_t max, _liberror_off_t returned, const char *fname)
+{
+	const char *desc;
+	struct liberror_error *error;
+	int saved_errno = errno;
+	liberror_save_backtrace(NULL);
+	if (returned < 0 || (size_t)returned < min) {
+		desc = "Seek resulted in a new offset in an earlier position than expected";
+	} else if (returned > max) {
+		desc = "Seek resulted in a new offset in an beyond the expectation";
+	} else {
+		desc = "Seek resulted in an unexpected new offset";
+	}
+	liberror_set_error(desc, "recv", "liberror-libc", LIBERROR_LIBC_ERRROR_SHORT_SEEK);
+	error = liberror_get_error();
+	error->details_type = LIBERROR_DETAILS_ONE_FILE;
+	error->details.one_file.fd = fd;
+	error->details.one_file.name = fname ? strdup(fname) : NULL;
+	error->details.one_file.role = "Seekable file";
+	errno = saved_errno;
+}
+
+
+_liberror_off_t
+liberror_lseek(int fd, _liberror_off_t offset, int whence, const char *fname)
+{
+	_liberror_off_t r = lseek(fd, offset, whence);
+	if (r >= 0)
+		return r;
+	liberror_save_backtrace(NULL);
+	liberror_lseek_failed(fd, offset, whence, fname);
+	return -1;
+}
+
+
+_liberror_off_t
+liberror_lseek_require(int fd, _liberror_off_t offset, int whence, _liberror_uoff_t min, _liberror_uoff_t max, const char *fname)
+{
+	_liberror_off_t r = lseek(fd, offset, whence);
+	if (r >= 0 && (_liberror_uoff_t)r >= min && (_liberror_uoff_t)r <= max)
+		return r;
+	liberror_save_backtrace(NULL);
+	if (r < 0)
+		liberror_lseek_failed(fd, offset, whence, fname);
+	else
+		liberror_lseek_short(fd, offset, whence, min, max, r, fname);
+	return -1;
+}