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rtld: Add -b option to allow to specify image name different from arg0.

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Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2020-05-31 22:37:33 +00:00
parent 6ecaf8f446
commit e82d19822e
2 changed files with 40 additions and 6 deletions
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14
libexec/rtld-elf/rtld.1
View File

@ -28,7 +28,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd May 20, 2017
.Dd June 1, 2020
.Dt RTLD 1
.Os
.Sh NAME
@ -302,6 +302,7 @@ Execution options may be specified.
The syntax of the direct invocation is
.Bd -ragged -offset indent
.Pa /libexec/ld-elf.so.1
.Op Fl b Ar exe
.Op Fl f Ar fd
.Op Fl p
.Op Fl -
@ -311,6 +312,17 @@ The syntax of the direct invocation is
.Pp
The options are:
.Bl -tag -width indent
.It Fl b Ar exe
Use the executable
.Fa exe
instead of
.Fa image_path
for activation.
If this option is specified,
.Ar image_path
is only used to provide the
.Va argv[0]
value to the program.
.It Fl f Ar fd
File descriptor
.Ar fd

32
libexec/rtld-elf/rtld.c
View File

@ -136,7 +136,8 @@ static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *);
static void objlist_remove(Objlist *, Obj_Entry *);
static int open_binary_fd(const char *argv0, bool search_in_path,
const char **binpath_res);
static int parse_args(char* argv[], int argc, bool *use_pathp, int *fdp);
static int parse_args(char* argv[], int argc, bool *use_pathp, int *fdp,
const char **argv0);
static int parse_integer(const char *);
static void *path_enumerate(const char *, path_enum_proc, const char *, void *);
static void print_usage(const char *argv0);
@ -467,8 +468,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
}
dbg("opening main program in direct exec mode");
if (argc >= 2) {
rtld_argc = parse_args(argv, argc, &search_in_path, &fd);
argv0 = argv[rtld_argc];
rtld_argc = parse_args(argv, argc, &search_in_path, &fd, &argv0);
explicit_fd = (fd != -1);
binpath = NULL;
if (!explicit_fd)
@ -5610,17 +5610,20 @@ open_binary_fd(const char *argv0, bool search_in_path,
* Parse a set of command-line arguments.
*/
static int
parse_args(char* argv[], int argc, bool *use_pathp, int *fdp)
parse_args(char* argv[], int argc, bool *use_pathp, int *fdp,
const char **argv0)
{
const char *arg;
char machine[64];
size_t sz;
int arglen, fd, i, j, mib[2];
char opt;
bool seen_b, seen_f;
dbg("Parsing command-line arguments");
*use_pathp = false;
*fdp = -1;
seen_b = seen_f = false;
for (i = 1; i < argc; i++ ) {
arg = argv[i];
@ -5647,7 +5650,21 @@ parse_args(char* argv[], int argc, bool *use_pathp, int *fdp)
if (opt == 'h') {
print_usage(argv[0]);
_exit(0);
} else if (opt == 'b') {
if (seen_f) {
_rtld_error("Both -b and -f specified");
rtld_die();
}
i++;
*argv0 = argv[i];
seen_b = true;
break;
} else if (opt == 'f') {
if (seen_b) {
_rtld_error("Both -b and -f specified");
rtld_die();
}
/*
* -f XX can be used to specify a
* descriptor for the binary named at
@ -5671,6 +5688,7 @@ parse_args(char* argv[], int argc, bool *use_pathp, int *fdp)
rtld_die();
}
*fdp = fd;
seen_f = true;
break;
} else if (opt == 'p') {
*use_pathp = true;
@ -5700,6 +5718,8 @@ parse_args(char* argv[], int argc, bool *use_pathp, int *fdp)
}
}
if (!seen_b)
*argv0 = argv[i];
return (i);
}
@ -5734,10 +5754,12 @@ static void
print_usage(const char *argv0)
{
rtld_printf("Usage: %s [-h] [-f <FD>] [-p] [--] <binary> [<args>]\n"
rtld_printf(
"Usage: %s [-h] [-b <exe>] [-f <FD>] [-p] [--] <binary> [<args>]\n"
"\n"
"Options:\n"
" -h Display this help message\n"
" -b <exe> Execute <exe> instead of <binary>, arg0 is <binary>\n"
" -f <FD> Execute <FD> instead of searching for <binary>\n"
" -p Search in PATH for named binary\n"
" -v Display identification information\n"