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Diffstat (limited to 'binutils-2.25/bfd/cache.c')
| -rw-r--r-- | binutils-2.25/bfd/cache.c | 645 |
1 files changed, 645 insertions, 0 deletions
diff --git a/binutils-2.25/bfd/cache.c b/binutils-2.25/bfd/cache.c new file mode 100644 index 00000000..4d46936b --- /dev/null +++ b/binutils-2.25/bfd/cache.c @@ -0,0 +1,645 @@ +/* BFD library -- caching of file descriptors. + + Copyright 1990, 1991, 1992, 1993, 1994, 1996, 2000, 2001, 2002, + 2003, 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc. + + Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com). + + This file is part of BFD, the Binary File Descriptor library. + + This program 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; either version 3 of the License, or + (at your option) any later version. + + This program 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 this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, + MA 02110-1301, USA. */ + +/* +SECTION + File caching + + The file caching mechanism is embedded within BFD and allows + the application to open as many BFDs as it wants without + regard to the underlying operating system's file descriptor + limit (often as low as 20 open files). The module in + <<cache.c>> maintains a least recently used list of + <<bfd_cache_max_open>> files, and exports the name + <<bfd_cache_lookup>>, which runs around and makes sure that + the required BFD is open. If not, then it chooses a file to + close, closes it and opens the one wanted, returning its file + handle. + +SUBSECTION + Caching functions +*/ + +#include "sysdep.h" +#include "bfd.h" +#include "libbfd.h" +#include "libiberty.h" +#include "bfd_stdint.h" + +#ifdef HAVE_MMAP +#include <sys/mman.h> +#endif + +/* In some cases we can optimize cache operation when reopening files. + For instance, a flush is entirely unnecessary if the file is already + closed, so a flush would use CACHE_NO_OPEN. Similarly, a seek using + SEEK_SET or SEEK_END need not first seek to the current position. + For stat we ignore seek errors, just in case the file has changed + while we weren't looking. If it has, then it's possible that the + file is shorter and we don't want a seek error to prevent us doing + the stat. */ +enum cache_flag { + CACHE_NORMAL = 0, + CACHE_NO_OPEN = 1, + CACHE_NO_SEEK = 2, + CACHE_NO_SEEK_ERROR = 4 +}; + +/* The maximum number of files which the cache will keep open at + one time. When needed call bfd_cache_max_open to initialize. */ + +static int max_open_files = 0; + +/* Set max_open_files, if not already set, to 12.5% of the allowed open + file descriptors, but at least 10, and return the value. */ +static int +bfd_cache_max_open (void) +{ + if (max_open_files == 0) + { + int max; +#ifdef HAVE_GETRLIMIT + struct rlimit rlim; + if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 + && rlim.rlim_cur != RLIM_INFINITY) + max = rlim.rlim_cur / 8; + else +#endif /* HAVE_GETRLIMIT */ +#ifdef _SC_OPEN_MAX + max = sysconf (_SC_OPEN_MAX) / 8; +#else + max = 10; +#endif /* _SC_OPEN_MAX */ + max_open_files = max < 10 ? 10 : max; + } + + return max_open_files; +} + +/* The number of BFD files we have open. */ + +static int open_files; + +/* Zero, or a pointer to the topmost BFD on the chain. This is + used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to + determine when it can avoid a function call. */ + +static bfd *bfd_last_cache = NULL; + +/* Insert a BFD into the cache. */ + +static void +insert (bfd *abfd) +{ + if (bfd_last_cache == NULL) + { + abfd->lru_next = abfd; + abfd->lru_prev = abfd; + } + else + { + abfd->lru_next = bfd_last_cache; + abfd->lru_prev = bfd_last_cache->lru_prev; + abfd->lru_prev->lru_next = abfd; + abfd->lru_next->lru_prev = abfd; + } + bfd_last_cache = abfd; +} + +/* Remove a BFD from the cache. */ + +static void +snip (bfd *abfd) +{ + abfd->lru_prev->lru_next = abfd->lru_next; + abfd->lru_next->lru_prev = abfd->lru_prev; + if (abfd == bfd_last_cache) + { + bfd_last_cache = abfd->lru_next; + if (abfd == bfd_last_cache) + bfd_last_cache = NULL; + } +} + +/* Close a BFD and remove it from the cache. */ + +static bfd_boolean +bfd_cache_delete (bfd *abfd) +{ + bfd_boolean ret; + + if (fclose ((FILE *) abfd->iostream) == 0) + ret = TRUE; + else + { + ret = FALSE; + bfd_set_error (bfd_error_system_call); + } + + snip (abfd); + + abfd->iostream = NULL; + --open_files; + + return ret; +} + +/* We need to open a new file, and the cache is full. Find the least + recently used cacheable BFD and close it. */ + +static bfd_boolean +close_one (void) +{ + register bfd *to_kill; + + if (bfd_last_cache == NULL) + to_kill = NULL; + else + { + for (to_kill = bfd_last_cache->lru_prev; + ! to_kill->cacheable; + to_kill = to_kill->lru_prev) + { + if (to_kill == bfd_last_cache) + { + to_kill = NULL; + break; + } + } + } + + if (to_kill == NULL) + { + /* There are no open cacheable BFD's. */ + return TRUE; + } + + to_kill->where = real_ftell ((FILE *) to_kill->iostream); + + return bfd_cache_delete (to_kill); +} + +/* Check to see if the required BFD is the same as the last one + looked up. If so, then it can use the stream in the BFD with + impunity, since it can't have changed since the last lookup; + otherwise, it has to perform the complicated lookup function. */ + +#define bfd_cache_lookup(x, flag) \ + ((x) == bfd_last_cache \ + ? (FILE *) (bfd_last_cache->iostream) \ + : bfd_cache_lookup_worker (x, flag)) + +/* Called when the macro <<bfd_cache_lookup>> fails to find a + quick answer. Find a file descriptor for @var{abfd}. If + necessary, it open it. If there are already more than + <<bfd_cache_max_open>> files open, it tries to close one first, to + avoid running out of file descriptors. It will return NULL + if it is unable to (re)open the @var{abfd}. */ + +static FILE * +bfd_cache_lookup_worker (bfd *abfd, enum cache_flag flag) +{ + bfd *orig_bfd = abfd; + if ((abfd->flags & BFD_IN_MEMORY) != 0) + abort (); + + while (abfd->my_archive) + abfd = abfd->my_archive; + + if (abfd->iostream != NULL) + { + /* Move the file to the start of the cache. */ + if (abfd != bfd_last_cache) + { + snip (abfd); + insert (abfd); + } + return (FILE *) abfd->iostream; + } + + if (flag & CACHE_NO_OPEN) + return NULL; + + if (bfd_open_file (abfd) == NULL) + ; + else if (!(flag & CACHE_NO_SEEK) + && real_fseek ((FILE *) abfd->iostream, abfd->where, SEEK_SET) != 0 + && !(flag & CACHE_NO_SEEK_ERROR)) + bfd_set_error (bfd_error_system_call); + else + return (FILE *) abfd->iostream; + + (*_bfd_error_handler) (_("reopening %B: %s\n"), + orig_bfd, bfd_errmsg (bfd_get_error ())); + return NULL; +} + +static file_ptr +cache_btell (struct bfd *abfd) +{ + FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN); + if (f == NULL) + return abfd->where; + return real_ftell (f); +} + +static int +cache_bseek (struct bfd *abfd, file_ptr offset, int whence) +{ + FILE *f = bfd_cache_lookup (abfd, whence != SEEK_CUR ? CACHE_NO_SEEK : CACHE_NORMAL); + if (f == NULL) + return -1; + return real_fseek (f, offset, whence); +} + +/* Note that archive entries don't have streams; they share their parent's. + This allows someone to play with the iostream behind BFD's back. + + Also, note that the origin pointer points to the beginning of a file's + contents (0 for non-archive elements). For archive entries this is the + first octet in the file, NOT the beginning of the archive header. */ + +static file_ptr +cache_bread_1 (struct bfd *abfd, void *buf, file_ptr nbytes) +{ + FILE *f; + file_ptr nread; + /* FIXME - this looks like an optimization, but it's really to cover + up for a feature of some OSs (not solaris - sigh) that + ld/pe-dll.c takes advantage of (apparently) when it creates BFDs + internally and tries to link against them. BFD seems to be smart + enough to realize there are no symbol records in the "file" that + doesn't exist but attempts to read them anyway. On Solaris, + attempting to read zero bytes from a NULL file results in a core + dump, but on other platforms it just returns zero bytes read. + This makes it to something reasonable. - DJ */ + if (nbytes == 0) + return 0; + + f = bfd_cache_lookup (abfd, CACHE_NORMAL); + if (f == NULL) + return 0; + +#if defined (__VAX) && defined (VMS) + /* Apparently fread on Vax VMS does not keep the record length + information. */ + nread = read (fileno (f), buf, nbytes); + /* Set bfd_error if we did not read as much data as we expected. If + the read failed due to an error set the bfd_error_system_call, + else set bfd_error_file_truncated. */ + if (nread == (file_ptr)-1) + { + bfd_set_error (bfd_error_system_call); + return -1; + } +#else + nread = fread (buf, 1, nbytes, f); + /* Set bfd_error if we did not read as much data as we expected. If + the read failed due to an error set the bfd_error_system_call, + else set bfd_error_file_truncated. */ + if (nread < nbytes && ferror (f)) + { + bfd_set_error (bfd_error_system_call); + return -1; + } +#endif + if (nread < nbytes) + /* This may or may not be an error, but in case the calling code + bails out because of it, set the right error code. */ + bfd_set_error (bfd_error_file_truncated); + return nread; +} + +static file_ptr +cache_bread (struct bfd *abfd, void *buf, file_ptr nbytes) +{ + file_ptr nread = 0; + + /* Some filesystems are unable to handle reads that are too large + (for instance, NetApp shares with oplocks turned off). To avoid + hitting this limitation, we read the buffer in chunks of 8MB max. */ + while (nread < nbytes) + { + const file_ptr max_chunk_size = 0x800000; + file_ptr chunk_size = nbytes - nread; + file_ptr chunk_nread; + + if (chunk_size > max_chunk_size) + chunk_size = max_chunk_size; + + chunk_nread = cache_bread_1 (abfd, (char *) buf + nread, chunk_size); + + /* Update the nread count. + + We just have to be careful of the case when cache_bread_1 returns + a negative count: If this is our first read, then set nread to + that negative count in order to return that negative value to the + caller. Otherwise, don't add it to our total count, or we would + end up returning a smaller number of bytes read than we actually + did. */ + if (nread == 0 || chunk_nread > 0) + nread += chunk_nread; + + if (chunk_nread < chunk_size) + break; + } + + return nread; +} + +static file_ptr +cache_bwrite (struct bfd *abfd, const void *where, file_ptr nbytes) +{ + file_ptr nwrite; + FILE *f = bfd_cache_lookup (abfd, CACHE_NORMAL); + + if (f == NULL) + return 0; + nwrite = fwrite (where, 1, nbytes, f); + if (nwrite < nbytes && ferror (f)) + { + bfd_set_error (bfd_error_system_call); + return -1; + } + return nwrite; +} + +static int +cache_bclose (struct bfd *abfd) +{ + return bfd_cache_close (abfd) - 1; +} + +static int +cache_bflush (struct bfd *abfd) +{ + int sts; + FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN); + + if (f == NULL) + return 0; + sts = fflush (f); + if (sts < 0) + bfd_set_error (bfd_error_system_call); + return sts; +} + +static int +cache_bstat (struct bfd *abfd, struct stat *sb) +{ + int sts; + FILE *f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR); + + if (f == NULL) + return -1; + sts = fstat (fileno (f), sb); + if (sts < 0) + bfd_set_error (bfd_error_system_call); + return sts; +} + +static void * +cache_bmmap (struct bfd *abfd ATTRIBUTE_UNUSED, + void *addr ATTRIBUTE_UNUSED, + bfd_size_type len ATTRIBUTE_UNUSED, + int prot ATTRIBUTE_UNUSED, + int flags ATTRIBUTE_UNUSED, + file_ptr offset ATTRIBUTE_UNUSED, + void **map_addr ATTRIBUTE_UNUSED, + bfd_size_type *map_len ATTRIBUTE_UNUSED) +{ + void *ret = (void *) -1; + + if ((abfd->flags & BFD_IN_MEMORY) != 0) + abort (); +#ifdef HAVE_MMAP + else + { + static uintptr_t pagesize_m1; + FILE *f; + file_ptr pg_offset; + bfd_size_type pg_len; + + f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR); + if (f == NULL) + return ret; + + if (pagesize_m1 == 0) + pagesize_m1 = getpagesize () - 1; + + /* Handle archive members. */ + if (abfd->my_archive != NULL) + offset += abfd->origin; + + /* Align. */ + pg_offset = offset & ~pagesize_m1; + pg_len = (len + (offset - pg_offset) + pagesize_m1) & ~pagesize_m1; + + ret = mmap (addr, pg_len, prot, flags, fileno (f), pg_offset); + if (ret == (void *) -1) + bfd_set_error (bfd_error_system_call); + else + { + *map_addr = ret; + *map_len = pg_len; + ret = (char *) ret + (offset & pagesize_m1); + } + } +#endif + + return ret; +} + +static const struct bfd_iovec cache_iovec = +{ + &cache_bread, &cache_bwrite, &cache_btell, &cache_bseek, + &cache_bclose, &cache_bflush, &cache_bstat, &cache_bmmap +}; + +/* +INTERNAL_FUNCTION + bfd_cache_init + +SYNOPSIS + bfd_boolean bfd_cache_init (bfd *abfd); + +DESCRIPTION + Add a newly opened BFD to the cache. +*/ + +bfd_boolean +bfd_cache_init (bfd *abfd) +{ + BFD_ASSERT (abfd->iostream != NULL); + if (open_files >= bfd_cache_max_open ()) + { + if (! close_one ()) + return FALSE; + } + abfd->iovec = &cache_iovec; + insert (abfd); + ++open_files; + return TRUE; +} + +/* +INTERNAL_FUNCTION + bfd_cache_close + +SYNOPSIS + bfd_boolean bfd_cache_close (bfd *abfd); + +DESCRIPTION + Remove the BFD @var{abfd} from the cache. If the attached file is open, + then close it too. + +RETURNS + <<FALSE>> is returned if closing the file fails, <<TRUE>> is + returned if all is well. +*/ + +bfd_boolean +bfd_cache_close (bfd *abfd) +{ + if (abfd->iovec != &cache_iovec) + return TRUE; + + if (abfd->iostream == NULL) + /* Previously closed. */ + return TRUE; + + return bfd_cache_delete (abfd); +} + +/* +FUNCTION + bfd_cache_close_all + +SYNOPSIS + bfd_boolean bfd_cache_close_all (void); + +DESCRIPTION + Remove all BFDs from the cache. If the attached file is open, + then close it too. + +RETURNS + <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is + returned if all is well. +*/ + +bfd_boolean +bfd_cache_close_all () +{ + bfd_boolean ret = TRUE; + + while (bfd_last_cache != NULL) + ret &= bfd_cache_close (bfd_last_cache); + + return ret; +} + +/* +INTERNAL_FUNCTION + bfd_open_file + +SYNOPSIS + FILE* bfd_open_file (bfd *abfd); + +DESCRIPTION + Call the OS to open a file for @var{abfd}. Return the <<FILE *>> + (possibly <<NULL>>) that results from this operation. Set up the + BFD so that future accesses know the file is open. If the <<FILE *>> + returned is <<NULL>>, then it won't have been put in the + cache, so it won't have to be removed from it. +*/ + +FILE * +bfd_open_file (bfd *abfd) +{ + abfd->cacheable = TRUE; /* Allow it to be closed later. */ + + if (open_files >= bfd_cache_max_open ()) + { + if (! close_one ()) + return NULL; + } + + switch (abfd->direction) + { + case read_direction: + case no_direction: + abfd->iostream = real_fopen (abfd->filename, FOPEN_RB); + break; + case both_direction: + case write_direction: + if (abfd->opened_once) + { + abfd->iostream = real_fopen (abfd->filename, FOPEN_RUB); + if (abfd->iostream == NULL) + abfd->iostream = real_fopen (abfd->filename, FOPEN_WUB); + } + else + { + /* Create the file. + + Some operating systems won't let us overwrite a running + binary. For them, we want to unlink the file first. + + However, gcc 2.95 will create temporary files using + O_EXCL and tight permissions to prevent other users from + substituting other .o files during the compilation. gcc + will then tell the assembler to use the newly created + file as an output file. If we unlink the file here, we + open a brief window when another user could still + substitute a file. + + So we unlink the output file if and only if it has + non-zero size. */ +#ifndef __MSDOS__ + /* Don't do this for MSDOS: it doesn't care about overwriting + a running binary, but if this file is already open by + another BFD, we will be in deep trouble if we delete an + open file. In fact, objdump does just that if invoked with + the --info option. */ + struct stat s; + + if (stat (abfd->filename, &s) == 0 && s.st_size != 0) + unlink_if_ordinary (abfd->filename); +#endif + abfd->iostream = real_fopen (abfd->filename, FOPEN_WUB); + abfd->opened_once = TRUE; + } + break; + } + + if (abfd->iostream == NULL) + bfd_set_error (bfd_error_system_call); + else + { + if (! bfd_cache_init (abfd)) + return NULL; + } + + return (FILE *) abfd->iostream; +} |