Blame src/internal/slibtool_symlink_impl.c

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/*******************************************************************/
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/*  slibtool: a skinny libtool implementation, written in C        */
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/*  Copyright (C) 2016--2021  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 <stdio.h>
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#include <string.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include "slibtool_driver_impl.h"
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#include "slibtool_errinfo_impl.h"
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#include "slibtool_symlink_impl.h"
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#include "slibtool_readlink_impl.h"
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#include "slibtool_snprintf_impl.h"
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#define SLBT_DEV_NULL_FLAGS	(SLBT_DRIVER_ALL_STATIC      \
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				| SLBT_DRIVER_DISABLE_SHARED \
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				| SLBT_DRIVER_DISABLE_STATIC)
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int slbt_create_symlink(
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	const struct slbt_driver_ctx *	dctx,
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	struct slbt_exec_ctx *		ectx,
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	const char *			target,
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	const char *			lnkname,
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	uint32_t			options)
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{
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	int		fdcwd;
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	int		fliteral;
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	int		fwrapper;
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	int		fdevnull;
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	char **		oargv;
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	const char *	slash;
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	char *		ln[5];
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	char *		dotdot;
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	char		tmplnk [PATH_MAX];
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	char		lnkarg [PATH_MAX];
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	char		alnkarg[PATH_MAX];
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	char		atarget[PATH_MAX];
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	char *		suffix = 0;
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	/* options */
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	fliteral = (options & SLBT_SYMLINK_LITERAL);
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	fwrapper = (options & SLBT_SYMLINK_WRAPPER);
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	fdevnull = (options & SLBT_SYMLINK_DEVNULL);
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	/* symlink is a placeholder? */
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	if (fliteral && fdevnull) {
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		slash = target;
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	} else if ((dctx->cctx->drvflags & SLBT_DEV_NULL_FLAGS)
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			&& !strcmp(target,"/dev/null")) {
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		slash  = target;
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		suffix = ".disabled";
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	/* target is an absolute path? */
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	} else if (fliteral) {
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		slash = target;
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	/* symlink target contains a dirname? */
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	} else if ((slash = strrchr(target,'/'))) {
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		slash++;
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	/* symlink target is a basename */
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	} else {
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		slash = target;
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	}
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	/* .la wrapper? */
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	dotdot = fwrapper ? "../" : "";
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	/* atarget */
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	if (slbt_snprintf(atarget,sizeof(atarget),
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			"%s%s",dotdot,slash) < 0)
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		return SLBT_BUFFER_ERROR(dctx);
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	/* tmplnk */
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	if (slbt_snprintf(tmplnk,sizeof(tmplnk),
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			"%s.symlink.tmp",
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			lnkname) <0)
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		return SLBT_BUFFER_ERROR(dctx);
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	/* placeholder? */
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	if (suffix) {
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		sprintf(alnkarg,"%s%s",lnkname,suffix);
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		lnkname = alnkarg;
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	}
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	/* lnkarg */
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	strcpy(lnkarg,lnkname);
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	/* ln argv (fake) */
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	ln[0] = "ln";
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	ln[1] = "-s";
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	ln[2] = atarget;
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	ln[3] = lnkarg;
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	ln[4] = 0;
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	oargv      = ectx->argv;
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	ectx->argv = ln;
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	/* step output */
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	if (!(dctx->cctx->drvflags & SLBT_DRIVER_SILENT)) {
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		if (dctx->cctx->mode == SLBT_MODE_LINK) {
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			if (slbt_output_link(dctx,ectx)) {
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				ectx->argv = oargv;
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				return SLBT_NESTED_ERROR(dctx);
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			}
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		} else {
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			if (slbt_output_install(dctx,ectx)) {
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				ectx->argv = oargv;
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				return SLBT_NESTED_ERROR(dctx);
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			}
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		}
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	}
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	/* restore execution context */
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	ectx->argv = oargv;
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	/* fdcwd */
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	fdcwd = slbt_driver_fdcwd(dctx);
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	/* create symlink */
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	if (symlinkat(atarget,fdcwd,tmplnk))
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		return SLBT_SYSTEM_ERROR(dctx,tmplnk);
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	return renameat(fdcwd,tmplnk,fdcwd,lnkname)
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		? SLBT_SYSTEM_ERROR(dctx,lnkname)
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		: 0;
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}
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int slbt_symlink_is_a_placeholder(int fdcwd, char * lnkpath)
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{
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	size_t		len;
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	char		slink [PATH_MAX];
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	char		target[PATH_MAX];
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	const char	suffix[] = ".disabled";
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	if ((sizeof(slink)-sizeof(suffix)) < (len=strlen(lnkpath)))
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		return 0;
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	memcpy(slink,lnkpath,len);
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	memcpy(&slink[len],suffix,sizeof(suffix));
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	return (!slbt_readlinkat(fdcwd,slink,target,sizeof(target)))
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		&& (!strcmp(target,"/dev/null"));
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}