X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-elf.c;h=e5b8a08f44141d0fd26ea0c346b43bfcb571c620;hb=97c7c238f60194565d4839e38e712414c22494e3;hp=f5c4f1a1c4988e2e323981e491071e2572f5f527;hpb=8e2aed3f18adc14ec586ef717e396bcac4473dd7;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-ust-elf.c b/liblttng-ust/lttng-ust-elf.c
index f5c4f1a1..e5b8a08f 100644
--- a/liblttng-ust/lttng-ust-elf.c
+++ b/liblttng-ust/lttng-ust-elf.c
@@ -16,10 +16,19 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
+#define _GNU_SOURCE
 #include <helper.h>
 #include <string.h>
 #include <lttng/align.h>
 #include <lttng/ust-elf.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include "lttng-tracer-core.h"
+
+#define BUF_LEN	4096
 
 /*
  * Retrieve the nth (where n is the `index` argument) phdr (program
@@ -32,7 +41,7 @@ struct lttng_ust_elf_phdr *lttng_ust_elf_get_phdr(struct lttng_ust_elf *elf,
 						uint16_t index)
 {
 	struct lttng_ust_elf_phdr *phdr = NULL;
-	long offset;
+	off_t offset;
 
 	if (!elf) {
 		goto error;
@@ -47,15 +56,17 @@ struct lttng_ust_elf_phdr *lttng_ust_elf_get_phdr(struct lttng_ust_elf *elf,
 		goto error;
 	}
 
-	offset = elf->ehdr->e_phoff + index * elf->ehdr->e_phentsize;
-	if (fseek(elf->file, offset, SEEK_SET)) {
+	offset = (off_t) elf->ehdr->e_phoff
+			+ (off_t) index * elf->ehdr->e_phentsize;
+	if (lseek(elf->fd, offset, SEEK_SET) < 0) {
 		goto error;
 	}
 
 	if (is_elf_32_bit(elf)) {
 		Elf32_Phdr elf_phdr;
 
-		if (!fread(&elf_phdr, sizeof(elf_phdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &elf_phdr, sizeof(elf_phdr))
+				< sizeof(elf_phdr)) {
 			goto error;
 		}
 		if (!is_elf_native_endian(elf)) {
@@ -65,7 +76,8 @@ struct lttng_ust_elf_phdr *lttng_ust_elf_get_phdr(struct lttng_ust_elf *elf,
 	} else {
 		Elf64_Phdr elf_phdr;
 
-		if (!fread(&elf_phdr, sizeof(elf_phdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &elf_phdr, sizeof(elf_phdr))
+				< sizeof(elf_phdr)) {
 			goto error;
 		}
 		if (!is_elf_native_endian(elf)) {
@@ -92,7 +104,7 @@ struct lttng_ust_elf_shdr *lttng_ust_elf_get_shdr(struct lttng_ust_elf *elf,
 						uint16_t index)
 {
 	struct lttng_ust_elf_shdr *shdr = NULL;
-	long offset;
+	off_t offset;
 
 	if (!elf) {
 		goto error;
@@ -107,15 +119,17 @@ struct lttng_ust_elf_shdr *lttng_ust_elf_get_shdr(struct lttng_ust_elf *elf,
 		goto error;
 	}
 
-	offset = elf->ehdr->e_shoff + index * elf->ehdr->e_shentsize;
-	if (fseek(elf->file, offset, SEEK_SET)) {
+	offset = (off_t) elf->ehdr->e_shoff
+			+ (off_t) index * elf->ehdr->e_shentsize;
+	if (lseek(elf->fd, offset, SEEK_SET) < 0) {
 		goto error;
 	}
 
 	if (is_elf_32_bit(elf)) {
 		Elf32_Shdr elf_shdr;
 
-		if (!fread(&elf_shdr, sizeof(elf_shdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &elf_shdr, sizeof(elf_shdr))
+				< sizeof(elf_shdr)) {
 			goto error;
 		}
 		if (!is_elf_native_endian(elf)) {
@@ -125,7 +139,8 @@ struct lttng_ust_elf_shdr *lttng_ust_elf_get_shdr(struct lttng_ust_elf *elf,
 	} else {
 		Elf64_Shdr elf_shdr;
 
-		if (!fread(&elf_shdr, sizeof(elf_shdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &elf_shdr, sizeof(elf_shdr))
+				< sizeof(elf_shdr)) {
 			goto error;
 		}
 		if (!is_elf_native_endian(elf)) {
@@ -149,10 +164,10 @@ error:
  * If no name is found, NULL is returned.
  */
 static
-char *lttng_ust_elf_get_section_name(struct lttng_ust_elf *elf, uint32_t offset)
+char *lttng_ust_elf_get_section_name(struct lttng_ust_elf *elf, off_t offset)
 {
 	char *name = NULL;
-	size_t len;
+	size_t len = 0, to_read;	/* len does not include \0 */
 
 	if (!elf) {
 		goto error;
@@ -162,34 +177,45 @@ char *lttng_ust_elf_get_section_name(struct lttng_ust_elf *elf, uint32_t offset)
 		goto error;
 	}
 
-	if (fseek(elf->file, elf->section_names_offset + offset, SEEK_SET)) {
+	if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) {
 		goto error;
 	}
-	/* Note that len starts at 1, it is not an index. */
-	for (len = 1; offset + len <= elf->section_names_size; ++len) {
-		switch (fgetc(elf->file)) {
-		case EOF:
+
+	to_read = elf->section_names_size - offset;
+
+	/* Find first \0 after or at current location, remember len. */
+	for (;;) {
+		char buf[BUF_LEN];
+		ssize_t read_len;
+		size_t i;
+
+		if (!to_read) {
 			goto error;
-		case '\0':
-			goto end;
-		default:
-			break;
 		}
+		read_len = lttng_ust_read(elf->fd, buf,
+			min_t(size_t, BUF_LEN, to_read));
+		if (read_len <= 0) {
+			goto error;
+		}
+		for (i = 0; i < read_len; i++) {
+			if (buf[i] == '\0') {
+				len += i;
+				goto end;
+			}
+		}
+		len += read_len;
+		to_read -= read_len;
 	}
-
-	/* No name was found before the end of the table. */
-	goto error;
-
 end:
-	name = zmalloc(sizeof(char) * len);
+	name = zmalloc(sizeof(char) * (len + 1));	/* + 1 for \0 */
 	if (!name) {
 		goto error;
 	}
-	if (fseek(elf->file, elf->section_names_offset + offset,
-		SEEK_SET)) {
+	if (lseek(elf->fd, elf->section_names_offset + offset,
+		SEEK_SET) < 0) {
 		goto error;
 	}
-	if (!fgets(name, len, elf->file)) {
+	if (lttng_ust_read(elf->fd, name, len + 1) < len + 1) {
 		goto error;
 	}
 
@@ -210,7 +236,7 @@ struct lttng_ust_elf *lttng_ust_elf_create(const char *path)
 {
 	uint8_t e_ident[EI_NIDENT];
 	struct lttng_ust_elf_shdr *section_names_shdr;
-	struct lttng_ust_elf *elf;
+	struct lttng_ust_elf *elf = NULL;
 
 	elf = zmalloc(sizeof(struct lttng_ust_elf));
 	if (!elf) {
@@ -222,17 +248,20 @@ struct lttng_ust_elf *lttng_ust_elf_create(const char *path)
 		goto error;
 	}
 
-	elf->file = fopen(elf->path, "rb");
-	if (!elf->file) {
+	elf->fd = open(elf->path, O_RDONLY | O_CLOEXEC);
+	if (elf->fd < 0) {
 		goto error;
 	}
 
-	if (!fread(e_ident, 1, EI_NIDENT, elf->file)) {
+	if (lttng_ust_read(elf->fd, e_ident, EI_NIDENT) < EI_NIDENT) {
 		goto error;
 	}
 	elf->bitness = e_ident[EI_CLASS];
 	elf->endianness = e_ident[EI_DATA];
-	rewind(elf->file);
+
+	if (lseek(elf->fd, 0, SEEK_SET) < 0) {
+		goto error;
+	}
 
 	elf->ehdr = zmalloc(sizeof(struct lttng_ust_elf_ehdr));
 	if (!elf->ehdr) {
@@ -242,7 +271,8 @@ struct lttng_ust_elf *lttng_ust_elf_create(const char *path)
 	if (is_elf_32_bit(elf)) {
 		Elf32_Ehdr elf_ehdr;
 
-		if (!fread(&elf_ehdr, sizeof(elf_ehdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr))
+				< sizeof(elf_ehdr)) {
 			goto error;
 		}
 		if (!is_elf_native_endian(elf)) {
@@ -252,7 +282,8 @@ struct lttng_ust_elf *lttng_ust_elf_create(const char *path)
 	} else {
 		Elf64_Ehdr elf_ehdr;
 
-		if (!fread(&elf_ehdr, sizeof(elf_ehdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr))
+				< sizeof(elf_ehdr)) {
 			goto error;
 		}
 		if (!is_elf_native_endian(elf)) {
@@ -270,19 +301,34 @@ struct lttng_ust_elf *lttng_ust_elf_create(const char *path)
 	elf->section_names_size = section_names_shdr->sh_size;
 
 	free(section_names_shdr);
-
 	return elf;
 
 error:
 	if (elf) {
 		free(elf->ehdr);
-		fclose(elf->file);
+		if (elf->fd >= 0) {
+			if (close(elf->fd)) {
+				abort();
+			}
+		}
 		free(elf->path);
+		free(elf);
 	}
-	free(elf);
 	return NULL;
 }
 
+/*
+ * Test whether the ELF file is position independent code (PIC)
+ */
+uint8_t lttng_ust_elf_is_pic(struct lttng_ust_elf *elf)
+{
+	/*
+	 * PIC has and e_type value of ET_DYN, see ELF specification
+	 * version 1.1 p. 1-3.
+	 */
+	return elf->ehdr->e_type == ET_DYN;
+}
+
 /*
  * Destroy the given lttng_ust_elf instance.
  */
@@ -293,7 +339,9 @@ void lttng_ust_elf_destroy(struct lttng_ust_elf *elf)
 	}
 
 	free(elf->ehdr);
-	fclose(elf->file);
+	if (close(elf->fd)) {
+		abort();
+	}
 	free(elf->path);
 	free(elf);
 }
@@ -307,7 +355,7 @@ void lttng_ust_elf_destroy(struct lttng_ust_elf *elf)
 int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz)
 {
 	uint16_t i;
-	uint64_t _memsz = 0;
+	uint64_t low_addr = UINT64_MAX, high_addr = 0;
 
 	if (!elf || !memsz) {
 		goto error;
@@ -315,7 +363,6 @@ int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz)
 
 	for (i = 0; i < elf->ehdr->e_phnum; ++i) {
 		struct lttng_ust_elf_phdr *phdr;
-		uint64_t align;
 
 		phdr = lttng_ust_elf_get_phdr(elf, i);
 		if (!phdr) {
@@ -330,27 +377,19 @@ int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz)
 			goto next_loop;
 		}
 
-		/*
-		 * A p_align of 0 means no alignment, i.e. aligned to
-		 * 1 byte.
-		 */
-		align = phdr->p_align == 0 ? 1 : phdr->p_align;
-		/* Align the start of the segment. */
-		_memsz += offset_align(_memsz, align);
-		_memsz += phdr->p_memsz;
-		/*
-		 * Add padding at the end of the segment, so it ends
-		 * on a multiple of the align value (which usually
-		 * means a page boundary). This makes the computation
-		 * valid even in cases where p_align would change from
-		 * one segment to the next.
-		 */
-		_memsz += offset_align(_memsz, align);
+		low_addr = min_t(uint64_t, low_addr, phdr->p_vaddr);
+		high_addr = max_t(uint64_t, high_addr,
+				phdr->p_vaddr + phdr->p_memsz);
 	next_loop:
 		free(phdr);
 	}
 
-	*memsz = _memsz;
+	if (high_addr < low_addr) {
+		/* No PT_LOAD segments or corrupted data. */
+		goto error;
+	}
+
+	*memsz = high_addr - low_addr;
 	return 0;
 error:
 	return -1;
@@ -371,14 +410,14 @@ error:
 static
 int lttng_ust_elf_get_build_id_from_segment(
 	struct lttng_ust_elf *elf, uint8_t **build_id, size_t *length,
-	uint64_t offset, uint64_t segment_end, int *found)
+	off_t offset, off_t segment_end)
 {
-	uint8_t *_build_id;
-	size_t _length;
-	int _found = 0;
+	uint8_t *_build_id = NULL;	/* Silence old gcc warning. */
+	size_t _length = 0;		/* Silence old gcc warning. */
 
 	while (offset < segment_end) {
 		struct lttng_ust_elf_nhdr nhdr;
+		size_t read_len;
 
 		/* Align start of note entry */
 		offset += offset_align(offset, ELF_NOTE_ENTRY_ALIGN);
@@ -390,10 +429,11 @@ int lttng_ust_elf_get_build_id_from_segment(
 		 * build id the data following the header will not
 		 * have been read.
 		 */
-		if (fseek(elf->file, offset, SEEK_SET)) {
+		if (lseek(elf->fd, offset, SEEK_SET) < 0) {
 			goto error;
 		}
-		if (!fread(&nhdr, sizeof(nhdr), 1, elf->file)) {
+		if (lttng_ust_read(elf->fd, &nhdr, sizeof(nhdr))
+				< sizeof(nhdr)) {
 			goto error;
 		}
 
@@ -418,29 +458,29 @@ int lttng_ust_elf_get_build_id_from_segment(
 
 		_length = nhdr.n_descsz;
 		_build_id = zmalloc(sizeof(uint8_t) * _length);
-		if (!build_id) {
+		if (!_build_id) {
 			goto error;
 		}
 
-		if (fseek(elf->file, offset, SEEK_SET)) {
+		if (lseek(elf->fd, offset, SEEK_SET) < 0) {
 			goto error;
 		}
-		if (!fread(_build_id, sizeof(*_build_id), _length, elf->file)) {
+		read_len = sizeof(*_build_id) * _length;
+		if (lttng_ust_read(elf->fd, _build_id, read_len) < read_len) {
 			goto error;
 		}
 
-		_found = 1;
 		break;
 	}
 
-	if (_found) {
+	if (_build_id) {
 		*build_id = _build_id;
 		*length = _length;
 	}
 
-	*found = _found;
 	return 0;
 error:
+	free(_build_id);
 	return -1;
 }
 
@@ -461,18 +501,17 @@ int lttng_ust_elf_get_build_id(struct lttng_ust_elf *elf, uint8_t **build_id,
 			size_t *length, int *found)
 {
 	uint16_t i;
-	uint8_t *_build_id;
-	size_t _length;
-	int _found = 0;
+	uint8_t *_build_id = NULL;	/* Silence old gcc warning. */
+	size_t _length = 0;		/* Silence old gcc warning. */
 
 	if (!elf || !build_id || !length || !found) {
 		goto error;
 	}
 
 	for (i = 0; i < elf->ehdr->e_phnum; ++i) {
-		uint64_t offset, segment_end;
+		off_t offset, segment_end;
 		struct lttng_ust_elf_phdr *phdr;
-		int ret;
+		int ret = 0;
 
 		phdr = lttng_ust_elf_get_phdr(elf, i);
 		if (!phdr) {
@@ -487,26 +526,28 @@ int lttng_ust_elf_get_build_id(struct lttng_ust_elf *elf, uint8_t **build_id,
 		offset = phdr->p_offset;
 		segment_end = offset + phdr->p_filesz;
 		ret = lttng_ust_elf_get_build_id_from_segment(
-			elf, &_build_id, &_length, offset, segment_end,
-			&_found);
+			elf, &_build_id, &_length, offset, segment_end);
 	next_loop:
 		free(phdr);
 		if (ret) {
 			goto error;
 		}
-		if (_found) {
+		if (_build_id) {
 			break;
 		}
 	}
 
-	if (_found) {
+	if (_build_id) {
 		*build_id = _build_id;
 		*length = _length;
+		*found = 1;
+	} else {
+		*found = 0;
 	}
 
-	*found = _found;
 	return 0;
 error:
+	free(_build_id);
 	return -1;
 }
 
@@ -520,18 +561,16 @@ error:
  *
  * Returns 0 on success, -1 if an error occurred.
  */
-static
 int lttng_ust_elf_get_debug_link_from_section(struct lttng_ust_elf *elf,
 					char **filename, uint32_t *crc,
-					int *found,
 					struct lttng_ust_elf_shdr *shdr)
 {
-	int _found = 0;
-	char *_filename;
+	char *_filename = NULL;		/* Silence old gcc warning. */
+	size_t filename_len;
 	char *section_name = NULL;
-	uint32_t _crc;
+	uint32_t _crc = 0;		/* Silence old gcc warning. */
 
-	if (!elf || !filename || !crc || !found || !shdr) {
+	if (!elf || !filename || !crc || !shdr) {
 		goto error;
 	}
 
@@ -560,37 +599,32 @@ int lttng_ust_elf_get_debug_link_from_section(struct lttng_ust_elf *elf,
 	if (!_filename) {
 		goto error;
 	}
-	if (fseek(elf->file, shdr->sh_offset, SEEK_SET)) {
+	if (lseek(elf->fd, shdr->sh_offset, SEEK_SET) < 0) {
 		goto error;
 	}
-	if (!fread(_filename, sizeof(*_filename), shdr->sh_size - ELF_CRC_SIZE,
-		elf->file)) {
+	filename_len = sizeof(*_filename) * (shdr->sh_size - ELF_CRC_SIZE);
+	if (lttng_ust_read(elf->fd, _filename, filename_len) < filename_len) {
 		goto error;
 	}
-	if (!fread(&_crc, sizeof(_crc), 1, elf->file)) {
+	if (lttng_ust_read(elf->fd, &_crc, sizeof(_crc)) < sizeof(_crc)) {
 		goto error;
 	}
 	if (!is_elf_native_endian(elf)) {
 		_crc = bswap_32(_crc);
 	}
 
-	_found = 1;
-
 end:
 	free(section_name);
-	if (_found) {
+	if (_filename) {
 		*filename = _filename;
 		*crc = _crc;
 	}
-	*found = _found;
 
 	return 0;
 
 error:
-	if (section_name) {
-		free(section_name);
-	}
-
+	free(_filename);
+	free(section_name);
 	return -1;
 }
 
@@ -609,9 +643,8 @@ int lttng_ust_elf_get_debug_link(struct lttng_ust_elf *elf, char **filename,
 {
 	int ret;
 	uint16_t i;
-	int _found = 0;
-	char *_filename;
-	uint32_t _crc;
+	char *_filename = NULL;		/* Silence old gcc warning. */
+	uint32_t _crc = 0;		/* Silence old gcc warning. */
 
 	if (!elf || !filename || !crc || !found) {
 		goto error;
@@ -626,24 +659,28 @@ int lttng_ust_elf_get_debug_link(struct lttng_ust_elf *elf, char **filename,
 		}
 
 		ret = lttng_ust_elf_get_debug_link_from_section(
-			elf, &_filename, &_crc, &_found, shdr);
+			elf, &_filename, &_crc, shdr);
 		free(shdr);
 
 		if (ret) {
 			goto error;
 		}
-		if (_found) {
+		if (_filename) {
 			break;
 		}
 	}
 
-	if (_found) {
+	if (_filename) {
 		*filename = _filename;
 		*crc = _crc;
+		*found = 1;
+	} else {
+		*found = 0;
 	}
 
-	*found = _found;
 	return 0;
+
 error:
+	free(_filename);
 	return -1;
 }