/*=export_func text_munmap
* private:
*
* what: unmap the data mapped in by text_mmap
*
* arg: tmap_info_t*, mapinfo, info about the mapping
*
* ret-type: int
* ret-desc: -1 or 0. @code{errno} will have the error code.
*
* doc:
*
* This routine will unmap the data mapped in with @code{text_mmap} and close
* the associated file descriptors opened by that function.
*
* see: munmap(2), close(2)
*
* err: Any error code issued by munmap(2) or close(2) is possible.
=*/
int
text_munmap(tmap_info_t * mi)
{
errno = 0;
#ifdef HAVE_MMAP
(void)munmap(mi->txt_data, mi->txt_full_size);
#else /* don't HAVE_MMAP */
/*
* IF the memory is writable *AND* it is not private (copy-on-write)
* *AND* the memory is "sharable" (seen by other processes)
* THEN rewrite the data. Emulate mmap visibility.
*/
if ( FILE_WRITABLE(mi->txt_prot, mi->txt_flags)
&& (lseek(mi->txt_fd, 0, SEEK_SET) >= 0) ) {
write(mi->txt_fd, mi->txt_data, mi->txt_size);
}
free(mi->txt_data);
#endif /* HAVE_MMAP */
mi->txt_errno = errno;
close_mmap_files(mi);
return mi->txt_errno;
}
/**
* Make sure all the parameters are correct: we have a file name that
* is a text file that we can read.
*
* @param fname the text file to map
* @param prot the memory protections requested (read/write/etc.)
* @param flags mmap flags
* @param mapinfo a structure holding everything we need to know
* about the mapping.
*/
static void
validate_mmap(char const * fname, int prot, int flags, tmap_info_t * mapinfo)
{
memset(mapinfo, 0, sizeof(*mapinfo));
#if defined(HAVE_MMAP) && ! defined(MAP_ANONYMOUS)
mapinfo->txt_zero_fd = AO_INVALID_FD;
#endif
mapinfo->txt_fd = AO_INVALID_FD;
mapinfo->txt_prot = prot;
mapinfo->txt_flags = flags;
/*
* Make sure we can stat the regular file. Save the file size.
*/
{
struct stat sb;
if (stat(fname, &sb) != 0) {
mapinfo->txt_errno = errno;
return;
}
if (! S_ISREG(sb.st_mode)) {
mapinfo->txt_errno = errno = EINVAL;
return;
}
mapinfo->txt_size = (size_t)sb.st_size;
}
/*
* Map mmap flags and protections into open flags and do the open.
*/
{
/*
* See if we will be updating the file. If we can alter the memory
* and if we share the data and we are *not* copy-on-writing the data,
* then our updates will show in the file, so we must open with
* write access.
*/
int o_flag = FILE_WRITABLE(prot, flags) ? O_RDWR : O_RDONLY;
/*
* If you're not sharing the file and you are writing to it,
* then don't let anyone else have access to the file.
*/
if (((flags & MAP_SHARED) == 0) && (prot & PROT_WRITE))
o_flag |= O_EXCL;
mapinfo->txt_fd = open(fname, o_flag);
}
if (mapinfo->txt_fd == AO_INVALID_FD)
mapinfo->txt_errno = errno;
}
/*=export_func text_munmap
* private:
*
* what: unmap the data mapped in by text_mmap
*
* arg: tmap_info_t*, mapinfo, info about the mapping
*
* ret-type: int
* ret-desc: -1 or 0. @file{errno} will have the error code.
*
* doc:
*
* This routine will unmap the data mapped in with @code{text_mmap} and close
* the associated file descriptors opened by that function.
*
* see: munmap(2), close(2)
*
* err: Any error code issued by munmap(2) or close(2) is possible.
=*/
int
text_munmap( tmap_info_t* pMI )
{
#ifdef HAVE_MMAP
int res = 0;
if (pMI->txt_alloc) {
/*
* IF the user has write permission and the text is not mapped private,
* then write back any changes. Hopefully, nobody else has modified
* the file in the mean time.
*/
if ( ((pMI->txt_prot & PROT_WRITE) != 0)
&& ((pMI->txt_flags & MAP_PRIVATE) == 0)) {
if (lseek(pMI->txt_fd, (size_t)0, SEEK_SET) != 0)
goto error_return;
res = (write( pMI->txt_fd, pMI->txt_data, pMI->txt_size ) < 0)
? errno : 0;
}
AGFREE( pMI->txt_data );
errno = res;
} else {
res = munmap( pMI->txt_data, pMI->txt_full_size );
}
if (res != 0)
goto error_return;
res = close( pMI->txt_fd );
if (res != 0)
goto error_return;
pMI->txt_fd = -1;
errno = 0;
if (pMI->txt_zero_fd != -1) {
res = close( pMI->txt_zero_fd );
pMI->txt_zero_fd = -1;
}
error_return:
pMI->txt_errno = errno;
return res;
#else /* HAVE_MMAP */
errno = 0;
/*
* IF the memory is writable *AND* it is not private (copy-on-write)
* *AND* the memory is "sharable" (seen by other processes)
* THEN rewrite the data.
*/
if ( FILE_WRITABLE(pMI->txt_prot, pMI->txt_flags)
&& (lseek( pMI->txt_fd, 0, SEEK_SET ) >= 0) ) {
write( pMI->txt_fd, pMI->txt_data, pMI->txt_size );
}
close( pMI->txt_fd );
pMI->txt_fd = -1;
pMI->txt_errno = errno;
free( pMI->txt_data );
return pMI->txt_errno;
#endif /* HAVE_MMAP */
}
/*=export_func text_mmap
* private:
*
* what: map a text file with terminating NUL
*
* arg: char const*, pzFile, name of the file to map
* arg: int, prot, mmap protections (see mmap(2))
* arg: int, flags, mmap flags (see mmap(2))
* arg: tmap_info_t*, mapinfo, returned info about the mapping
*
* ret-type: void*
* ret-desc: The mmaped data address
*
* doc:
*
* This routine will mmap a file into memory ensuring that there is at least
* one @file{NUL} character following the file data. It will return the
* address where the file contents have been mapped into memory. If there is a
* problem, then it will return @code{MAP_FAILED} and set @file{errno}
* appropriately.
*
* The named file does not exist, @code{stat(2)} will set @file{errno} as it
* will. If the file is not a regular file, @file{errno} will be
* @code{EINVAL}. At that point, @code{open(2)} is attempted with the access
* bits set appropriately for the requested @code{mmap(2)} protections and flag
* bits. On failure, @file{errno} will be set according to the documentation
* for @code{open(2)}. If @code{mmap(2)} fails, @file{errno} will be set as
* that routine sets it. If @code{text_mmap} works to this point, a valid
* address will be returned, but there may still be ``issues''.
*
* If the file size is not an even multiple of the system page size, then
* @code{text_map} will return at this point and @file{errno} will be zero.
* Otherwise, an anonymous map is attempted. If not available, then an attempt
* is made to @code{mmap(2)} @file{/dev/zero}. If any of these fail, the
* address of the file's data is returned, bug @code{no} @file{NUL} characters
* are mapped after the end of the data.
*
* see: mmap(2), open(2), stat(2)
*
* err: Any error code issued by mmap(2), open(2), stat(2) is possible.
* Additionally, if the specified file is not a regular file, then
* errno will be set to @code{EINVAL}.
*
* example:
* #include <mylib.h>
* tmap_info_t mi;
* int no_nul;
* void* data = text_mmap( "file", PROT_WRITE, MAP_PRIVATE, &mi );
* if (data == MAP_FAILED) return;
* no_nul = (mi.txt_size == mi.txt_full_size);
* << use the data >>
* text_munmap( &mi );
=*/
void*
text_mmap( char const* pzFile, int prot, int flags, tmap_info_t* pMI )
{
memset( pMI, 0, sizeof(*pMI) );
#ifdef HAVE_MMAP
pMI->txt_zero_fd = -1;
#endif
pMI->txt_fd = -1;
/*
* Make sure we can stat the regular file. Save the file size.
*/
{
struct stat sb;
if (stat( pzFile, &sb ) != 0) {
pMI->txt_errno = errno;
return MAP_FAILED_PTR;
}
if (! S_ISREG( sb.st_mode )) {
pMI->txt_errno = errno = EINVAL;
return MAP_FAILED_PTR;
}
pMI->txt_size = sb.st_size;
}
/*
* Map mmap flags and protections into open flags and do the open.
*/
{
int o_flag;
/*
* See if we will be updating the file. If we can alter the memory
* and if we share the data and we are *not* copy-on-writing the data,
* then our updates will show in the file, so we must open with
* write access.
*/
if (FILE_WRITABLE(prot,flags))
o_flag = O_RDWR;
else
o_flag = O_RDONLY;
/*
* If you're not sharing the file and you are writing to it,
* then don't let anyone else have access to the file.
*/
if (((flags & MAP_SHARED) == 0) && (prot & PROT_WRITE))
o_flag |= O_EXCL;
pMI->txt_fd = open( pzFile, o_flag );
}
if (pMI->txt_fd == AO_INVALID_FD) {
pMI->txt_errno = errno;
return MAP_FAILED_PTR;
}
#ifdef HAVE_MMAP /* * * * * WITH MMAP * * * * * */
/*
* do the mmap. If we fail, then preserve errno, close the file and
* return the failure.
*/
pMI->txt_data =
mmap(NULL, pMI->txt_size+1, prot, flags, pMI->txt_fd, (size_t)0);
if (pMI->txt_data == MAP_FAILED_PTR) {
pMI->txt_errno = errno;
goto fail_return;
}
/*
* Most likely, everything will turn out fine now. The only difficult
* part at this point is coping with files with sizes that are a multiple
* of the page size. Handling that is what this whole thing is about.
*/
pMI->txt_zero_fd = -1;
pMI->txt_errno = 0;
{
void* pNuls;
#ifdef _SC_PAGESIZE
size_t pgsz = sysconf(_SC_PAGESIZE);
#else
size_t pgsz = getpagesize();
#endif
/*
* Compute the pagesize rounded mapped memory size.
* IF this is not the same as the file size, then there are NUL's
* at the end of the file mapping and all is okay.
*/
pMI->txt_full_size = (pMI->txt_size + (pgsz - 1)) & ~(pgsz - 1);
if (pMI->txt_size != pMI->txt_full_size)
return pMI->txt_data;
/*
* Still here? We have to remap the trailing inaccessible page
* either anonymously or to /dev/zero.
*/
pMI->txt_full_size += pgsz;
#if defined(MAP_ANONYMOUS)
pNuls = mmap(
(void*)(((char*)pMI->txt_data) + pMI->txt_size),
pgsz, PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_FIXED|MAP_PRIVATE, AO_INVALID_FD, (size_t)0);
if (pNuls != MAP_FAILED_PTR)
return pMI->txt_data;
pMI->txt_errno = errno;
#elif defined(HAVE_DEV_ZERO)
pMI->txt_zero_fd = open( "/dev/zero", O_RDONLY );
if (pMI->txt_zero_fd == AO_INVALID_FD) {
pMI->txt_errno = errno;
} else {
pNuls = mmap(
(void*)(((char*)pMI->txt_data) + pMI->txt_size), pgsz,
PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED,
pMI->txt_zero_fd, 0 );
if (pNuls != MAP_FAILED_PTR)
return pMI->txt_data;
pMI->txt_errno = errno;
close( pMI->txt_zero_fd );
pMI->txt_zero_fd = -1;
}
#endif
pMI->txt_full_size = pMI->txt_size;
}
{
void* p = AGALOC( pMI->txt_size+1, "file text" );
memcpy( p, pMI->txt_data, pMI->txt_size );
((char*)p)[pMI->txt_size] = NUL;
munmap(pMI->txt_data, pMI->txt_size );
pMI->txt_data = p;
}
pMI->txt_alloc = 1;
return pMI->txt_data;
#else /* * * * * * no HAVE_MMAP * * * * * */
pMI->txt_data = AGALOC( pMI->txt_size+1, "file text" );
if (pMI->txt_data == NULL) {
pMI->txt_errno = ENOMEM;
goto fail_return;
}
{
size_t sz = pMI->txt_size;
char* pz = pMI->txt_data;
while (sz > 0) {
ssize_t rdct = read( pMI->txt_fd, pz, sz );
if (rdct <= 0) {
pMI->txt_errno = errno;
fprintf( stderr, zFSErrReadFile,
errno, strerror( errno ), pzFile );
free( pMI->txt_data );
goto fail_return;
}
pz += rdct;
sz -= rdct;
}
*pz = NUL;
}
/*
* We never need a dummy page mapped in
*/
pMI->txt_zero_fd = -1;
pMI->txt_errno = 0;
return pMI->txt_data;
#endif /* * * * * * no HAVE_MMAP * * * * * */
fail_return:
if (pMI->txt_fd >= 0) {
close( pMI->txt_fd );
pMI->txt_fd = -1;
}
errno = pMI->txt_errno;
pMI->txt_data = MAP_FAILED_PTR;
return pMI->txt_data;
}