prefixes in the list, including the first.
For example, if the prefix +/elsewhere+ should be added to all
-pathnames for a program +prgrm+ then the command line might be:
+pathnames for a program _prgrm_ then the command line might be:
----
PATHMAPNOT=/elsewhere LD_PRELOAD=libpathmap.so prgrm
----
-However, if +prgrm+ is a dynamically linked executable, then all
-libraries
+Note however that dynamically linked libraries are loaded via
+statically linked function calls and they are therefore not handled
+via libpathmap.so.
ENVIRONMENT
-----------
#include <errno.h>
static int (*real_open)(const char *pathname, int flags);
-static FILE *(*real_openat)(int dirfd, const char *pathname, int flags);
+static int (*real_openat)(int dirfd, const char *pathname, int flags);
static FILE *(*real_fopen)(const char *pathname, const char *mode);
// The environment variable name
// Try opening the pathname in the tar
static FILE *tryopentar(const char *pathname) {
- fprintf( stderr, "libtarmap: %s\n", pathname );
+ //fprintf( stderr, "libtarmap open: %s\n", pathname );
if ( bsearch( &pathname, data.table, data.count, sizeof( char * ),
alphaorder ) ) {
char *p = join( data.head, pathname );
- fprintf( stderr, "libtarmap: => %s\n", p );
+ //fprintf( stderr, "libtarmap: => %s\n", p );
FILE *file = popen_notarmap( p );
free( p );
return file;
}
// Override "openat"
-FILE *openat(int dirfd, const char *pathname, int flags) {
+int openat(int dirfd, const char *pathname, int flags) {
+ //fprintf( stderr, "openat( %s )\n", pathname );
if ( data.tarmap ) {
- if ( strncmp( pathname, "/", 1 ) == 0 ) {
- FILE *file = tryopentar( pathname + 1 );
- if ( file ) {
- return file;
- }
+ FILE *file = tryopentar( pathname );
+ if ( file ) {
+ return fileno( file );
}
}
return ( real_openat )? real_openat( dirfd, pathname, flags ) : 0;
// Override "open"
int open(const char *pathname, int flags) {
+ //fprintf( stderr, "open( %s )\n", pathname );
if ( data.tarmap ) {
- if ( strncmp( pathname, "/", 1 ) == 0 ) {
- FILE *file = tryopentar( pathname + 1 );
- if ( file ) {
- return fileno( file );
- }
+ FILE *file = tryopentar( pathname );
+ if ( file ) {
+ return fileno( file );
}
}
return ( real_open )? real_open( pathname, flags ) : -1;
// Override "fopen"
FILE *fopen(const char *pathname, const char *mode) {
if ( data.tarmap ) {
- if ( strncmp( pathname, "/", 1 ) == 0 ) {
- FILE *file = tryopentar( pathname + 1 );
- if ( file ) {
- return file;
- }
+ FILE *file = tryopentar( pathname );
+ if ( file ) {
+ return file;
}
}
return ( real_fopen )? real_fopen( pathname, mode ) : 0;
* Initialize the dynamic library.
*/
void so_init() {
+ static int done = 0;
+ if ( done ) {
+ return;
+ }
+ done = 1;
void *lib = dlopen( "libc.so.6", RTLD_LAZY );
real_open = dlsym( lib, "open" );
real_openat = dlsym( lib, "openat" );
real_fopen = dlsym( lib, "fopen" );
char *tarfile = getenv( TARMAP );
if ( tarfile == 0 || *tarfile == 0 ) {
- fprintf( stderr, "(libtarmap: no tar)\n" );
+ //fprintf( stderr, "(libtarmap: no tar)\n" );
data.tarmap = 0;
return; // Stop here for unset or cleared environment
}
- fprintf( stderr, "libtarmap: tarfile = %s\n", tarfile );
+ //fprintf( stderr, "libtarmap: tarfile = %s\n", tarfile );
if ( ( data.tarmap = realpath( tarfile, 0 ) ) == 0 ) {
// Cannot find the tar file .. that's total badness!
perror( tarfile );
SYNOPSYS
--------
-+LD_PRELOAD=libtarmap.so+ +TARMAP=+_tarfile_ _command_
+LD_PRELOAD=libtarmap.so TARMAP=_tarfile_ _command_
DESCRIPTION
-----------
-This dynamic library, libtarmap.so, is intended to be used as a
-"preload" library for programs for which pathnames are to be mapped to
-a different common prefix. The effect is somewhat similar to +chroot+
-in that absolute pathnames, which normally are from the root of the
-file system, get mapped to be relative to the choosen prefix point.
-
-+libtarmap.so+ is "configured" by setting environment variable
-+PATHMAPNOT+ to be the path prefixes, given as a colon separated list,
-that +libtarmap.so+ should be concerned with. The first of them is
-then used as the prefix to add to the program's pathnames (when
-opening files) except to those pathnames that start with any of the
-prefixes in the list, including the first.
-
-For example, if the prefix +/elsewhere+ should be added to all
-pathnames for a program +prgrm+ then the command line might be:
-
-----
-PATHMAPNOT=/elsewhere LD_PRELOAD=libtarmap.so prgrm
-----
-
-However, if +prgrm+ is a dynamically linked executable, then all
-libraries
+This is a dynamic library that is intended to be used as an LD_PRELOAD
+library for programs for which pathnames are to be mapped into a
+tarfile first. In fact the command may be a bash script file within
+the tarfile for executing that
ENVIRONMENT
-----------
-PATHMAPNOT::
+TARMAP::
-This environment variable tells which path prefixes, given as a colon
-separated list, +libtarmap.so+ should be concerned with. The first
-prefix is the one to add to all pathnames except to those of any of
-the prefixes in the list.
+This environment variable tells which tarfile to use. Pathnames are
+looked up in the tarfile first.
EXAMPLES
--------
-Assume there is a directory +/home/test/extra+
-
-----
-env PATHMAPNOT=/home/test:/proc:/dev:/lib:/usr:/bin \
- LD_PRELOAD=libtarmap.so \
- ls /extra
-----
-
SEE ALSO
--------
-tarmap::
-
-aaa
-
-libpathmap.so::
-aaa
DESCRIPTION
-----------
+The given command is executed by "/bin/bash" with an LD_PRELOAD
+setting to use libtarmap.so for resolving pathnames into the given tar
+file before the filesystem. See libtarmap.so for more details.
+
TBD
This dynamic library, libtarmap.so, is intended to be used as a
fprintf( stderr, "%s\n", "*** tarmap: OOM .. exiting" );
exit( 1 );
}
+ //fprintf( stderr, ":%s:\n", old );
return old;
}
int main(int argc,char *argv[],char *envp[]) {
- if ( argc < 3 ) {
+ if ( argc < 2 ) {
fprintf( stderr, "tarmap tar-file command [ argument ]\n" );
exit( 1 );
}
int i_preload = -1;
int i_tarmap = -1;
for ( n = 0; envp[n]; n++) {
- if ( strcmp( envp[n], "LD_PRELOAD=" ) == 0 ) {
+ if ( strncmp( envp[n], "LD_PRELOAD=", 11 ) == 0 ) {
i_preload = n;
- } else if ( strcmp( envp[n], "TARMAP=" ) ) {
+ } else if ( strncmp( envp[n], "TARMAP=", 7 ) == 0 ) {
i_tarmap = n;
}
}
memcpy( nenvp, envp, n * sizeof( char*) );
nenvp[ i_preload ] = makeEnv( "LD_PRELOAD", "libtarmap.so" );
nenvp[ i_tarmap ] = makeEnv( "TARMAP", argv[1] );
- execve( argv[2], argv+2, nenvp );
+ execve( "/bin/bash", argv+1, nenvp );
perror( "tarmap exec" );
return 1;
}
projects / rrq / pathmap.git / commitdiff