diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/allocator.h | 45 | ||||
| -rw-r--r-- | lib/careadlinkat.c | 179 | ||||
| -rw-r--r-- | lib/careadlinkat.h | 67 | ||||
| -rw-r--r-- | lib/gnulib.mk | 10 |
4 files changed, 300 insertions, 1 deletions
diff --git a/lib/allocator.h b/lib/allocator.h new file mode 100644 index 00000000000..54cc5ff66f0 --- /dev/null +++ b/lib/allocator.h @@ -0,0 +1,45 @@ +/* Memory allocators such as malloc+free. + + Copyright (C) 2011 Free Software Foundation, Inc. + + 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, see <http://www.gnu.org/licenses/>. */ + +/* Written by Paul Eggert. */ + +#ifndef _GL_ALLOCATOR_H + +#include <stddef.h> + +struct allocator +{ + /* Call MALLOC to allocate memory, like 'malloc'. On failure MALLOC + should return NULL, though not necessarily set errno. When given + a zero size it may return NULL even if successful. */ + void *(*malloc) (size_t); + + /* If nonnull, call REALLOC to reallocate memory, like 'realloc'. + On failure REALLOC should return NULL, though not necessarily set + errno. When given a zero size it may return NULL even if + successful. */ + void *(*realloc) (void *, size_t); + + /* Call FREE to free memory, like 'free'. */ + void (*free) (void *); + + /* If nonnull, call DIE if MALLOC or REALLOC fails. DIE should + not return. */ + void (*die) (void); +}; + +#endif diff --git a/lib/careadlinkat.c b/lib/careadlinkat.c new file mode 100644 index 00000000000..828c0508db7 --- /dev/null +++ b/lib/careadlinkat.c @@ -0,0 +1,179 @@ +/* Read symbolic links into a buffer without size limitation, relative to fd. + + Copyright (C) 2001, 2003-2004, 2007, 2009-2011 Free Software Foundation, + Inc. + + 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, see <http://www.gnu.org/licenses/>. */ + +/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */ + +#include <config.h> + +#include "careadlinkat.h" + +#include "allocator.h" + +#include <errno.h> +#include <limits.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +/* Use the system functions, not the gnulib overrides, because this + module does not depend on GNU or POSIX semantics. */ +#undef malloc +#undef realloc + +/* Define this independently so that stdint.h is not a prerequisite. */ +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif + +#ifndef SSIZE_MAX +# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) +#endif + +#if ! HAVE_READLINKAT +/* Ignore FD. Get the symbolic link value of FILENAME and put it into + BUFFER, with size BUFFER_SIZE. This function acts like readlink + but has readlinkat's signature. */ +ssize_t +careadlinkatcwd (int fd, char const *filename, char *buffer, + size_t buffer_size) +{ + (void) fd; + return readlink (filename, buffer, buffer_size); +} +#endif + +/* Assuming the current directory is FD, get the symbolic link value + of FILENAME as a null-terminated string and put it into a buffer. + If FD is AT_FDCWD, FILENAME is interpreted relative to the current + working directory, as in openat. + + If the link is small enough to fit into BUFFER put it there. + BUFFER's size is BUFFER_SIZE, and BUFFER can be null + if BUFFER_SIZE is zero. + + If the link is not small, put it into a dynamically allocated + buffer managed by ALLOC. It is the caller's responsibility to free + the returned value if it is nonnull and is not BUFFER. A null + ALLOC stands for the standard allocator. + + The PREADLINKAT function specifies how to read links. + + If successful, return the buffer address; otherwise return NULL and + set errno. */ + +char * +careadlinkat (int fd, char const *filename, + char *buffer, size_t buffer_size, + struct allocator const *alloc, + ssize_t (*preadlinkat) (int, char const *, char *, size_t)) +{ + char *buf; + size_t buf_size; + size_t buf_size_max = + SSIZE_MAX < SIZE_MAX ? (size_t) SSIZE_MAX + 1 : SIZE_MAX; + char stack_buf[1024]; + + void *(*pmalloc) (size_t) = malloc; + void *(*prealloc) (void *, size_t) = realloc; + void (*pfree) (void *) = free; + void (*pdie) (void) = NULL; + if (alloc) + { + pmalloc = alloc->malloc; + prealloc = alloc->realloc; + pfree = alloc->free; + pdie = alloc->die; + } + + if (! buffer_size) + { + /* Allocate the initial buffer on the stack. This way, in the + common case of a symlink of small size, we get away with a + single small malloc() instead of a big malloc() followed by a + shrinking realloc(). */ + buffer = stack_buf; + buffer_size = sizeof stack_buf; + } + + buf = buffer; + buf_size = buffer_size; + + do + { + /* Attempt to read the link into the current buffer. */ + ssize_t link_length = preadlinkat (fd, filename, buf, buf_size); + size_t link_size; + if (link_length < 0) + { + /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1 + with errno == ERANGE if the buffer is too small. */ + int readlinkat_errno = errno; + if (readlinkat_errno != ERANGE) + { + if (buf != buffer) + { + pfree (buf); + errno = readlinkat_errno; + } + return NULL; + } + } + + link_size = link_length; + + if (link_size < buf_size) + { + buf[link_size++] = '\0'; + + if (buf == stack_buf) + { + char *b = (char *) pmalloc (link_size); + if (! b) + break; + memcpy (b, buf, link_size); + buf = b; + } + else if (link_size < buf_size && buf != buffer && prealloc) + { + /* Shrink BUF before returning it. */ + char *b = (char *) prealloc (buf, link_size); + if (b) + buf = b; + } + + return buf; + } + + if (buf != buffer) + pfree (buf); + + if (buf_size <= buf_size_max / 2) + buf_size *= 2; + else if (buf_size < buf_size_max) + buf_size = buf_size_max; + else + break; + buf = (char *) pmalloc (buf_size); + } + while (buf); + + if (pdie) + pdie (); + errno = ENOMEM; + return NULL; +} diff --git a/lib/careadlinkat.h b/lib/careadlinkat.h new file mode 100644 index 00000000000..c5e4bcfc15f --- /dev/null +++ b/lib/careadlinkat.h @@ -0,0 +1,67 @@ +/* Read symbolic links into a buffer without size limitation, relative to fd. + + Copyright (C) 2011 Free Software Foundation, Inc. + + 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, see <http://www.gnu.org/licenses/>. */ + +/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */ + +#ifndef _GL_CAREADLINKAT_H + +#include <fcntl.h> +#include <unistd.h> + +struct allocator; + +/* Assuming the current directory is FD, get the symbolic link value + of FILENAME as a null-terminated string and put it into a buffer. + If FD is AT_FDCWD, FILENAME is interpreted relative to the current + working directory, as in openat. + + If the link is small enough to fit into BUFFER put it there. + BUFFER's size is BUFFER_SIZE, and BUFFER can be null + if BUFFER_SIZE is zero. + + If the link is not small, put it into a dynamically allocated + buffer managed by ALLOC. It is the caller's responsibility to free + the returned value if it is nonnull and is not BUFFER. + + The PREADLINKAT function specifies how to read links. + + If successful, return the buffer address; otherwise return NULL and + set errno. */ + +char *careadlinkat (int fd, char const *filename, + char *buffer, size_t buffer_size, + struct allocator const *alloc, + ssize_t (*preadlinkat) (int, char const *, + char *, size_t)); + +/* Suitable values for careadlinkat's FD and PREADLINKAT arguments, + when doing a plain readlink. */ +#if HAVE_READLINKAT +# define careadlinkatcwd readlinkat +#else +/* Define AT_FDCWD independently, so that the careadlinkat module does + not depend on the fcntl-h module. The value does not matter, since + careadlinkatcwd ignores it, but we might as well use the same value + as fcntl-h. */ +# ifndef AT_FDCWD +# define AT_FDCWD (-3041965) +# endif +ssize_t careadlinkatcwd (int fd, char const *filename, + char *buffer, size_t buffer_size); +#endif + +#endif /* _GL_CAREADLINKAT_H */ diff --git a/lib/gnulib.mk b/lib/gnulib.mk index 030f95b7a68..bb5bdcf852e 100644 --- a/lib/gnulib.mk +++ b/lib/gnulib.mk @@ -9,7 +9,7 @@ # the same distribution terms as the rest of that program. # # Generated by gnulib-tool. -# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=. --makefile-name=gnulib.mk --no-libtool --macro-prefix=gl --no-vc-files crypto/md5 dtoastr filemode getloadavg getopt-gnu ignore-value intprops lstat mktime readlink socklen stdio strftime symlink sys_stat +# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=. --makefile-name=gnulib.mk --no-libtool --macro-prefix=gl --no-vc-files careadlinkat crypto/md5 dtoastr filemode getloadavg getopt-gnu ignore-value intprops lstat mktime readlink socklen stdio strftime symlink sys_stat MOSTLYCLEANFILES += core *.stackdump @@ -69,6 +69,14 @@ EXTRA_DIST += $(top_srcdir)/./c++defs.h ## end gnulib module c++defs +## begin gnulib module careadlinkat + +libgnu_a_SOURCES += careadlinkat.c + +EXTRA_DIST += allocator.h careadlinkat.h + +## end gnulib module careadlinkat + ## begin gnulib module crypto/md5 |