diff options
Diffstat (limited to 'libdwfl/dwfl_file.c')
| -rw-r--r-- | libdwfl/dwfl_file.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/libdwfl/dwfl_file.c b/libdwfl/dwfl_file.c new file mode 100644 index 00000000..c7927d02 --- /dev/null +++ b/libdwfl/dwfl_file.c @@ -0,0 +1,281 @@ +/* Find debugging and symbol information for a module in libdwfl. + Copyright (C) 2005, 2006, 2007 Red Hat, Inc. + This file is part of Red Hat elfutils. + + Red Hat elfutils is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by the + Free Software Foundation; version 2 of the License. + + Red Hat elfutils is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License along + with Red Hat elfutils; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. + + In addition, as a special exception, Red Hat, Inc. gives You the + additional right to link the code of Red Hat elfutils with code licensed + under any Open Source Initiative certified open source license + (http://www.opensource.org/licenses/index.php) which requires the + distribution of source code with any binary distribution and to + distribute linked combinations of the two. Non-GPL Code permitted under + this exception must only link to the code of Red Hat elfutils through + those well defined interfaces identified in the file named EXCEPTION + found in the source code files (the "Approved Interfaces"). The files + of Non-GPL Code may instantiate templates or use macros or inline + functions from the Approved Interfaces without causing the resulting + work to be covered by the GNU General Public License. Only Red Hat, + Inc. may make changes or additions to the list of Approved Interfaces. + Red Hat's grant of this exception is conditioned upon your not adding + any new exceptions. If you wish to add a new Approved Interface or + exception, please contact Red Hat. You must obey the GNU General Public + License in all respects for all of the Red Hat elfutils code and other + code used in conjunction with Red Hat elfutils except the Non-GPL Code + covered by this exception. If you modify this file, you may extend this + exception to your version of the file, but you are not obligated to do + so. If you do not wish to provide this exception without modification, + you must delete this exception statement from your version and license + this file solely under the GPL without exception. + + Red Hat elfutils is an included package of the Open Invention Network. + An included package of the Open Invention Network is a package for which + Open Invention Network licensees cross-license their patents. No patent + license is granted, either expressly or impliedly, by designation as an + included package. Should you wish to participate in the Open Invention + Network licensing program, please visit www.openinventionnetwork.com + <http://www.openinventionnetwork.com>. */ + +#include <config.h> +#include "../libelf/libelfP.h" /* For elf->map_address. */ +#undef _ + +#include "libdwflP.h" + +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> +#include <fcntl.h> + +struct cache_key +{ + dev_t dev; + ino64_t ino; + struct timespec ctim; + size_t refcount; +}; + +struct cache_entry +{ + struct dwfl_shared_file shared; + struct cache_key key; + + struct cache_entry *next; +}; + +static struct cache_entry *cache = NULL; + +static struct cache_entry * +lookup_entry (struct stat64 *s) +{ + for (struct cache_entry *entry = cache; entry != NULL; entry = entry->next) + if (entry->key.dev == s->st_dev + && entry->key.ino == s->st_ino + && entry->key.ctim.tv_nsec == s->st_ctim.tv_nsec + && entry->key.ctim.tv_sec == s->st_ctim.tv_sec) + return entry; + return NULL; +} + +Dwfl_Error +internal_function +__libdwfl_open_file (struct dwfl_file *tgt, + const char *file_name, + int fd, Elf *elf) +{ + if (tgt->shared != NULL) + return tgt->shared->elferr; + + Dwfl_Error error; + if (fd < 0 + && elf == NULL + && unlikely ((fd = open64 (file_name, O_RDONLY)) < 0)) + { + tgt->shared = NULL; + return DWFL_E (ERRNO, errno); + } + + struct cache_entry *entry = NULL; + bool synthetic = false; + struct stat64 s; + + /* If we get there and fd < 0, it's ELF without file backing. */ + if (fd >= 0) + { + if (unlikely (fstat64 (fd, &s) < 0)) + { + tgt->shared = NULL; + return DWFL_E (ERRNO, errno); + } + + /* Reuse cache entry if possible. */ + entry = lookup_entry (&s); + if (entry != NULL) + { + /* Consume elf. */ + if (elf != NULL) + elf_end (elf); + + /* Consume the fd. We don't need it when reusing. */ + if (fd >= 0 && unlikely (close (fd) < 0)) + { + tgt->shared = NULL; + return DWFL_E (ERRNO, errno); + } + + ++entry->key.refcount; + tgt->shared = &entry->shared; + return entry->shared.elferr; + } + } + else + synthetic = true; + + /* Failing that, enlist a new entry. */ + entry = calloc (1, sizeof *entry); + if (unlikely (entry == NULL)) + { + error = DWFL_E_NOMEM; + goto fail; + } + + entry->next = cache; + cache = entry; + + /* For synthetic files, the key is left initialized to zero. */ + if (!synthetic) + { + entry->key.dev = s.st_dev; + entry->key.ino = s.st_ino; + entry->key.ctim = s.st_ctim; + } + entry->key.refcount = 1; + + tgt->shared = &entry->shared; + tgt->name = file_name ? strdup (file_name) : NULL; + + if (elf == NULL) + { + elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL); + if (unlikely (elf == NULL)) + { + error = DWFL_E_LIBELF; + goto fail; + } + } + if (!synthetic + && elf->map_address != NULL + && elf_cntl (elf, ELF_C_FDREAD) == 0) + { + close (fd); + fd = -1; + } + entry->shared.elf = elf; + entry->shared.fd = fd; + + GElf_Ehdr ehdr_mem; + GElf_Ehdr *ehdr = gelf_getehdr (entry->shared.elf, &ehdr_mem); + if (unlikely (ehdr == NULL)) + { + error = DWFL_E_LIBELF; + goto fail; + } + + for (uint_fast16_t i = 0; i < ehdr->e_phnum; ++i) + { + GElf_Phdr ph_mem; + GElf_Phdr *ph = gelf_getphdr (entry->shared.elf, i, &ph_mem); + if (ph == NULL) + { + error = DWFL_E_LIBELF; + goto fail; + } + if (ph->p_type == PT_LOAD) + { + entry->shared.start = ph->p_vaddr; + entry->shared.align = ph->p_align; + break; + } + } + + return entry->shared.elferr = DWFL_E_NOERROR; + + + /* Upon failure, keep the shared file open, but cache error. */ + fail: + if (fd != -1) + { + /* Consume the FD, even if the caller opened it. We don't check + for success, because if it failed, which error should we pass up? */ + close (fd); + entry->shared.fd = -1; + } + + if (elf != NULL) + { + elf_end (elf); + entry->shared.elf = NULL; + } + + error = __libdwfl_canon_error (error); + if (entry != NULL) + entry->shared.elferr = error; + return error; +} + +void +internal_function +__libdwfl_close_file (struct dwfl_file *tgt) +{ + if (likely (tgt->shared != NULL)) + { + /* Look up the file in cache. With singly linked list, we can't + simply cast file to entry, we need the prev pointer. */ + struct cache_entry *entry; + struct cache_entry **prevp = &cache; + for (entry = cache; entry != NULL; + entry = *(prevp = &entry->next)) + if (&entry->shared == tgt->shared) + break; + assert (entry != NULL); + + if (--entry->key.refcount == 0) + { + if (entry->shared.elf != NULL) + elf_end (entry->shared.elf); + if (entry->shared.fd != -1) + close (entry->shared.fd); + + if (tgt->shared->dw != NULL) + INTUSE(dwarf_end) (tgt->shared->dw); + + if (tgt->shared->ebl != NULL) + ebl_closebackend (tgt->shared->ebl); + + *prevp = entry->next; + free (entry); + + if (BUILD_ID_PTR (entry->shared.build_id)) + free (entry->shared.build_id); + } + + tgt->shared = NULL; + } + + if (tgt->name != NULL) + { + free (tgt->name); + tgt->name = NULL; + } +} |