Blame src/logic/slbt_exec_execute.c

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/*******************************************************************/
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/*  slibtool: a skinny libtool implementation, written in C        */
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/*  Copyright (C) 2016--2024  SysDeer Technologies, LLC            */
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/*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
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/*******************************************************************/
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#include <string.h>
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#include <stdbool.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <sys/stat.h>
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#include <slibtool/slibtool.h>
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#include "slibtool_spawn_impl.h"
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#include "slibtool_driver_impl.h"
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#include "slibtool_snprintf_impl.h"
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#include "slibtool_errinfo_impl.h"
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/*******************************************************************/
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/* --mode=execute: wrapper script and execution argument vector    */
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/*                                                                 */
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/* The purpose of executable wrapper scripts is to properly handle */
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/* one common scenario where:                                      */
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/*                                                                 */
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/* (1) a build project would entail both executable programs and   */
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/*     dynamically linked libraries; and                           */
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/*                                                                 */
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/* (2) one or more of the project's executable programs would have */
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/*     one or more of the project's libraries as a dynamic runtime */
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/*     dependency.                                                 */
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/*                                                                 */
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/* Since the project's dependency libraries are not yet installed, */
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/* correct resolution of a program's dynamic library dependencies  */
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/* must depend on an appropriate setting of the LD_LIBRARY_PATH    */
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/* encironment variable (on Linxu or Midipix) or an equivalent     */
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/* environment variable on any of the other supported platforms.   */
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/*                                                                 */
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/* Here, too, there are two distinct cases:                        */
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/*                                                                 */
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/* (a) the executable wrapper script is directly invoked from the  */
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/*     shell command line or otherwise; or                         */
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/*                                                                 */
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/* (b) the build target associated with the executable program is  */
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/*     an argument passed to `slibtool --mode=execute` either as   */
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/*     the name of the program to be executed (and thus as the     */
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/*     first non-slibtool argument) or for processing by another   */
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/*     program.                                                    */
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/*                                                                 */
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/* The first case is handled entirely from within the executable   */
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/* wrapper script. The load environment variable is set based on   */
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/* the path that was stored in it by slibtool at link time, and    */
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/* the real executable is then exec'ed.                            */
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/*                                                                 */
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/* In the second case, slibtool would start by testing whether the */
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/* first non-slibtool argument is the wrapper script of a newly    */
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/* built executable program. If it is, then slibtool would invoke  */
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/* the wrapper script rather than the executable program, and add  */
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/* the path to the executable to the argument vector before all    */
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/* other arguments, makign it ${1} from the wrapper script's point */
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/* of view. Then again, and irrespective of the previous step,     */
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/* slibtool will replace any remaining command-line argument which */
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/* points to a build target associated with a newly built program  */
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/* with the path to the program itself (that is, the one located   */
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/* under the internal .libs/ directory).                           */
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/*                                                                 */
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/* For the sake of consistency and robustness, wrapper scripts are */
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/* created at link time for _all_ executable programs, including   */
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/* those programs which appear to have system libraries as their   */
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/* sole dynamic library dependencies.                              */
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/*******************************************************************/
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static int slbt_argument_is_an_executable_wrapper_script(
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	const struct slbt_driver_ctx *  dctx,
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	const char *                    arg,
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	char                            (*altarg)[PATH_MAX])
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{
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	int           fdcwd;
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	const char *  base;
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	char *        mark;
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	struct stat   st;
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	/* the extra characters: .libs/.exe.wrapper */
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	if (strlen(arg) > (PATH_MAX - 20))
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		return SLBT_BUFFER_ERROR(dctx);
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	/* path/to/progname --> path/to/.libs/progname.exe.wapper */
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	if ((base = strrchr(arg,'/')))
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		base++;
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	if (!base)
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		base = arg;
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	mark  = *altarg;
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	mark += base - arg;
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	strcpy(*altarg,arg);
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	mark += sprintf(mark,".libs/%s",base);
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	strcpy(mark,".exe.wrapper");
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	/* not an executable wrapper script? */
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	fdcwd = slbt_driver_fdcwd(dctx);
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	if (fstatat(fdcwd,*altarg,&st,0) < 0)
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		return (errno == ENOENT)
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			? 0 : SLBT_SYSTEM_ERROR(dctx,*altarg);
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	/* path/to/.libs/progname.exe.wapper --> path/to/.libs/progname */
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	*mark = '\0';
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	return 1;
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}
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int slbt_exec_execute(const struct slbt_driver_ctx * dctx)
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{
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	int			ret;
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	char **                 parg;
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	char **                 aarg;
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	char *			program;
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	char *                  exeref;
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	char			wrapper[PATH_MAX];
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	char			exeprog[PATH_MAX];
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	char			argbuf [PATH_MAX];
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	struct slbt_exec_ctx *	ectx;
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	/* dry run */
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	if (dctx->cctx->drvflags & SLBT_DRIVER_DRY_RUN)
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		return 0;
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	/* context */
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	if (slbt_ectx_get_exec_ctx(dctx,&ectx) < 0)
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		return SLBT_NESTED_ERROR(dctx);
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	slbt_disable_placeholders(ectx);
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	/* original and alternate argument vectors */
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	parg = ectx->cargv;
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	aarg = ectx->altv;
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	/* program (first non-slibtool argument) */
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	if (!(program = ectx->cargv[0]))
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		return SLBT_CUSTOM_ERROR(
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			dctx,
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			SLBT_ERR_FLOW_ERROR);
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	/* init the wrapper argument based on the first qualifying argument */
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	for (exeref=0; !exeref && *parg; parg++) {
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		strcpy(argbuf,*parg);
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		if ((ret = slbt_argument_is_an_executable_wrapper_script(
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				dctx,argbuf,&exeprog)) < 0) {
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			return SLBT_NESTED_ERROR(dctx);
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		} else if (ret == 1) {
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			sprintf(wrapper,"%s.exe.wrapper",exeprog);
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			exeref  = *parg;
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			*aarg++ = wrapper;
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		} else {
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			strcpy(*parg,argbuf);
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		}
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	}
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	/* transform in place as needed all arguments */
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	for (parg=ectx->cargv; *parg; parg++) {
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		if ((ret = slbt_argument_is_an_executable_wrapper_script(
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				dctx,*parg,&argbuf)) < 0) {
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			return SLBT_NESTED_ERROR(dctx);
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		} else if (ret == 1) {
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			strcpy(*parg,argbuf);
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			*aarg++ = *parg;
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		} else {
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			*aarg++ = *parg;
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		}
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	}
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	*aarg = 0;
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	/* execute mode */
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	ectx->program = ectx->altv[0];
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	ectx->argv    = ectx->altv;
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	/* step output */
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	if (!(dctx->cctx->drvflags & SLBT_DRIVER_SILENT)) {
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		if (slbt_output_execute(ectx)) {
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			slbt_ectx_free_exec_ctx(ectx);
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			return SLBT_NESTED_ERROR(dctx);
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		}
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	}
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	execvp(ectx->altv[0],ectx->altv);
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	slbt_ectx_free_exec_ctx(ectx);
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	return SLBT_SYSTEM_ERROR(dctx,0);
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}