From b1a2817ada5a4c26977f747d8c69295e9ee061e6 Mon Sep 17 00:00:00 2001 From: Jonas 'Sortie' Termansen Date: Tue, 23 Sep 2014 19:18:17 +0200 Subject: [PATCH] Add symbolic link support to cp(1). --- utils/cp.cpp | 157 +++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 127 insertions(+), 30 deletions(-) diff --git a/utils/cp.cpp b/utils/cp.cpp index 35fea6fc..4b7d6039 100644 --- a/utils/cp.cpp +++ b/utils/cp.cpp @@ -68,23 +68,29 @@ const int FLAG_VERBOSE = 1 << 1; const int FLAG_TARGET_DIR = 1 << 2; const int FLAG_NO_TARGET_DIR = 1 << 3; const int FLAG_UPDATE = 1 << 4; -const int FLAG_NO_DEREFERENCE = 1 << 5; -const int FLAG_DEREFERENCE = 1 << 6; -const int FLAG_DEREFERENCE_ARGUMENTS = 1 << 7; + +enum symbolic_dereference +{ + SYMBOLIC_DEREFERENCE_NONE, + SYMBOLIC_DEREFERENCE_ARGUMENTS, + SYMBOLIC_DEREFERENCE_ALWAYS, + SYMBOLIC_DEREFERENCE_DEFAULT, +}; bool CopyFileContents(int srcfd, const char* srcpath, int dstfd, const char* dstpath, int flags); bool CopyDirectoryContents(int srcfd, const char* srcpath, - int dstfd, const char* dstpath, int flags); + int dstfd, const char* dstpath, int flags, + enum symbolic_dereference symbolic_dereference); bool CopyToDest(int srcdirfd, const char* srcrel, const char* srcpath, int dstdirfd, const char* dstrel, const char* dstpath, - int flags); + int flags, enum symbolic_dereference symbolic_dereference); bool CopyIntoDirectory(int srcdirfd, const char* srcrel, const char* srcpath, int dstdirfd, const char* dstrel, const char* dstpath, - int flags); + int flags, enum symbolic_dereference symbolic_dereference); bool CopyAmbigious(int srcdirfd, const char* srcrel, const char* srcpath, int dstdirfd, const char* dstrel, const char* dstpath, - int flags); + int flags, enum symbolic_dereference symbolic_dereference); bool CopyFileContents(int srcfd, const char* srcpath, int dstfd, const char* dstpath, int flags) @@ -152,7 +158,8 @@ bool CopyFileContents(int srcfd, const char* srcpath, } bool CopyDirectoryContentsInner(DIR* srcdir, const char* srcpath, - DIR* dstdir, const char* dstpath, int flags) + DIR* dstdir, const char* dstpath, int flags, + enum symbolic_dereference symbolic_dereference) { if ( flags & FLAG_VERBOSE ) printf("`%s' -> `%s'\n", srcpath, dstpath); @@ -166,7 +173,8 @@ bool CopyDirectoryContentsInner(DIR* srcdir, const char* srcpath, char* srcpath_new = AddElemToPath(srcpath, name); char* dstpath_new = AddElemToPath(dstpath, name); bool ok = CopyToDest(dirfd(srcdir), name, srcpath_new, - dirfd(dstdir), name, dstpath_new, flags); + dirfd(dstdir), name, dstpath_new, flags, + symbolic_dereference); free(srcpath_new); free(dstpath_new); if ( !ok ) @@ -176,7 +184,8 @@ bool CopyDirectoryContentsInner(DIR* srcdir, const char* srcpath, } bool CopyDirectoryContentsOuter(int srcfd, const char* srcpath, - int dstfd, const char* dstpath, int flags) + int dstfd, const char* dstpath, int flags, + enum symbolic_dereference symbolic_dereference) { struct stat srcst, dstst; if ( fstat(srcfd, &srcst) < 0 ) @@ -201,14 +210,15 @@ bool CopyDirectoryContentsOuter(int srcfd, const char* srcpath, if ( !dstdir ) return error(0, errno, "fdopendir()"), closedir(srcdir), false; bool ret = CopyDirectoryContentsInner(srcdir, srcpath, dstdir, dstpath, - flags); + flags, symbolic_dereference); closedir(dstdir); closedir(srcdir); return ret; } bool CopyDirectoryContents(int srcfd, const char* srcpath, - int dstfd, const char* dstpath, int flags) + int dstfd, const char* dstpath, int flags, + enum symbolic_dereference symbolic_dereference) { int srcfd_copy = dup(srcfd); if ( srcfd_copy < 0 ) @@ -217,7 +227,8 @@ bool CopyDirectoryContents(int srcfd, const char* srcpath, if ( dstfd_copy < 0 ) return error(0, errno, "dup"), close(srcfd_copy), false; bool ret = CopyDirectoryContentsOuter(srcfd_copy, srcpath, - dstfd_copy, dstpath, flags); + dstfd_copy, dstpath, flags, + symbolic_dereference); close(dstfd_copy); close(srcfd_copy); return ret; @@ -225,11 +236,14 @@ bool CopyDirectoryContents(int srcfd, const char* srcpath, bool CopyToDest(int srcdirfd, const char* srcrel, const char* srcpath, int dstdirfd, const char* dstrel, const char* dstpath, - int flags) + int flags, enum symbolic_dereference symbolic_dereference) { struct stat srcst; bool ret = false; - int srcfd = openat(srcdirfd, srcrel, O_RDONLY); + int srcfd_flags = O_RDONLY; + if ( symbolic_dereference == SYMBOLIC_DEREFERENCE_NONE ) + srcfd_flags |= O_SYMLINK_NOFOLLOW; + int srcfd = openat(srcdirfd, srcrel, O_RDONLY | srcfd_flags); if ( srcfd < 0 ) { error(0, errno, "%s", srcpath); @@ -240,7 +254,74 @@ bool CopyToDest(int srcdirfd, const char* srcrel, const char* srcpath, error(0, errno, "stat: %s", srcpath); return close(srcfd), false; } - if ( S_ISDIR(srcst.st_mode) ) + if ( symbolic_dereference == SYMBOLIC_DEREFERENCE_ARGUMENTS ) + symbolic_dereference = SYMBOLIC_DEREFERENCE_NONE; + // TODO: I'm really not satisfied with the atomicity properties in this case. + if ( S_ISLNK(srcst.st_mode) ) + { + // TODO: How to handle the update flag in this case? + struct stat dstst; + int dstst_ret = fstatat(dstdirfd, dstrel, &dstst, AT_SYMLINK_NOFOLLOW); + if ( dstst_ret < 0 && errno != ENOENT ) + { + error(0, errno, "%s", dstpath); + return close(srcfd), false; + } + bool already_is_symlink = false; + if ( dstst_ret == 0 ) + { + if ( S_ISLNK(dstst.st_mode) ) + { + already_is_symlink = true; + } + else if ( S_ISDIR(dstst.st_mode) ) + { + error(0, 0, "cannot overwrite directory `%s' with non-directory", + dstpath); + return close(srcfd), false; + } + else + { + if ( unlinkat(dstdirfd, dstrel, 0) == 0 ) + { + if ( flags & FLAG_VERBOSE ) + printf("removed `%s'\n", dstpath); + } + else if ( errno != ENOENT ) + { + error(0, errno, "unlink: %s", dstpath); + return close(srcfd), false; + } + } + } + if ( !already_is_symlink ) + { + if ( symlinkat("", dstdirfd, dstrel) < 0 ) + { + error(0, errno, "creating symlink: %s", dstpath); + return close(srcfd), false; + } + } + int dstfd = openat(dstdirfd, dstrel, O_WRONLY | O_SYMLINK_NOFOLLOW); + if ( dstfd < 0 ) + { + error(0, errno, "creating and opening symlink: %s", dstpath); + return close(srcfd), false; + } + if ( fstat(dstfd, &dstst) < 0 ) + { + error(0, errno, "stat of symlink: %s", dstpath); + return close(dstfd), close(srcfd), false; + } + if ( !S_ISLNK(dstst.st_mode) ) + { + error(0, errno, "unexpectedly not a symlink: %s", dstpath); + return close(dstfd), close(srcfd), false; + } + ret = CopyFileContents(srcfd, srcpath, dstfd, dstpath, flags); + close(dstfd); + } + else if ( S_ISDIR(srcst.st_mode) ) { if ( !(flags & FLAG_RECURSIVE) ) { @@ -266,7 +347,8 @@ bool CopyToDest(int srcdirfd, const char* srcrel, const char* srcpath, return close(srcfd), false; } } - ret = CopyDirectoryContents(srcfd, srcpath, dstfd, dstpath, flags); + ret = CopyDirectoryContents(srcfd, srcpath, dstfd, dstpath, flags, + symbolic_dereference); close(dstfd); } else @@ -296,7 +378,7 @@ bool CopyToDest(int srcdirfd, const char* srcrel, const char* srcpath, bool CopyIntoDirectory(int srcdirfd, const char* srcrel, const char* srcpath, int dstdirfd, const char* dstrel, const char* dstpath, - int flags) + int flags, enum symbolic_dereference symbolic_dereference) { const char* src_basename = BaseName(srcrel); int dstfd = openat(dstdirfd, dstrel, O_RDONLY | O_DIRECTORY); @@ -307,14 +389,15 @@ bool CopyIntoDirectory(int srcdirfd, const char* srcrel, const char* srcpath, } char* dstpath_new = AddElemToPath(dstpath, src_basename); bool ret = CopyToDest(srcdirfd, srcrel, srcpath, - dstfd, src_basename, dstpath_new, flags); + dstfd, src_basename, dstpath_new, + flags, symbolic_dereference); free(dstpath_new); return ret; } bool CopyAmbigious(int srcdirfd, const char* srcrel, const char* srcpath, int dstdirfd, const char* dstrel, const char* dstpath, - int flags) + int flags, enum symbolic_dereference symbolic_dereference) { struct stat dstst; if ( fstatat(dstdirfd, dstrel, &dstst, 0) < 0 ) @@ -328,10 +411,12 @@ bool CopyAmbigious(int srcdirfd, const char* srcrel, const char* srcpath, } if ( S_ISDIR(dstst.st_mode) ) return CopyIntoDirectory(srcdirfd, srcrel, srcpath, - dstdirfd, dstrel, dstpath, flags); + dstdirfd, dstrel, dstpath, + flags, symbolic_dereference); else return CopyToDest(srcdirfd, srcrel, srcpath, - dstdirfd, dstrel, dstpath, flags); + dstdirfd, dstrel, dstpath, + flags, symbolic_dereference); } void compact_arguments(int* argc, char*** argv) @@ -373,6 +458,7 @@ int main(int argc, char* argv[]) int flags = 0; const char* target_directory = NULL; const char* preserve_list = NULL; + enum symbolic_dereference symbolic_dereference = SYMBOLIC_DEREFERENCE_DEFAULT; for ( int i = 1; i < argc; i++ ) { const char* arg = argv[i]; @@ -395,8 +481,8 @@ int main(int argc, char* argv[]) case 'o': if ( *(arg + 1) ) arg = "o"; else if ( i + 1 != argc ) argv[++i] = NULL; break; case 's': /* ignored */ break; #endif - case 'H': flags |= FLAG_DEREFERENCE_ARGUMENTS; break; - case 'L': flags |= FLAG_DEREFERENCE; break; + case 'H': symbolic_dereference = SYMBOLIC_DEREFERENCE_ARGUMENTS; break; + case 'L': symbolic_dereference = SYMBOLIC_DEREFERENCE_ALWAYS; break; case 'r': case 'R': flags |= FLAG_RECURSIVE; break; case 'v': flags |= FLAG_VERBOSE; break; @@ -422,7 +508,7 @@ int main(int argc, char* argv[]) case 'T': flags |= FLAG_NO_TARGET_DIR; break; case 'u': flags |= FLAG_UPDATE; break; case 'p': preserve_list = "mode,ownership,timestamps"; break; - case 'P': flags |= FLAG_NO_DEREFERENCE; break; + case 'P': symbolic_dereference = SYMBOLIC_DEREFERENCE_NONE; break; default: #ifdef CP_PRETEND_TO_BE_INSTALL fprintf(stderr, "%s (fake): unknown option, ignoring -- '%c'\n", argv0, c); @@ -438,7 +524,7 @@ int main(int argc, char* argv[]) else if ( !strcmp(arg, "--version") ) version(stdout, argv0), exit(0); else if ( !strcmp(arg, "--dereference") ) - flags |= FLAG_DEREFERENCE; + symbolic_dereference = SYMBOLIC_DEREFERENCE_ALWAYS; else if ( !strcmp(arg, "--recursive") ) flags |= FLAG_RECURSIVE; else if ( !strcmp(arg, "--verbose") ) @@ -469,7 +555,7 @@ int main(int argc, char* argv[]) else if ( !strcmp(arg, "--update") ) flags |= FLAG_UPDATE; else if ( !strcmp(arg, "--no-dereference") ) - flags |= FLAG_NO_DEREFERENCE; + symbolic_dereference = SYMBOLIC_DEREFERENCE_NONE; else { #ifdef CP_PRETEND_TO_BE_INSTALL @@ -485,6 +571,14 @@ int main(int argc, char* argv[]) if ( (flags & FLAG_TARGET_DIR) && (flags & FLAG_NO_TARGET_DIR) ) error(1, 0, "cannot combine --target-directory (-t) and --no-target-directory (-T)"); + if ( symbolic_dereference == SYMBOLIC_DEREFERENCE_DEFAULT ) + { + if ( flags & FLAG_RECURSIVE ) + symbolic_dereference = SYMBOLIC_DEREFERENCE_NONE; + else + symbolic_dereference = SYMBOLIC_DEREFERENCE_ALWAYS; + } + // TODO: Actually preserve. (void) preserve_list; @@ -501,7 +595,8 @@ int main(int argc, char* argv[]) const char* dst = argv[2]; if ( 3 < argc ) error(1, 0, "extra operand `%s'", argv[3]); - return CopyToDest(AT_FDCWD, src, src, AT_FDCWD, dst, dst, flags) ? 0 : 1; + return CopyToDest(AT_FDCWD, src, src, AT_FDCWD, dst, dst, flags, + symbolic_dereference) ? 0 : 1; } if ( !(flags & FLAG_TARGET_DIR) && argc <= 3 ) @@ -512,7 +607,8 @@ int main(int argc, char* argv[]) const char* dst = argv[2]; if ( 3 < argc ) error(1, 0, "extra operand `%s'", argv[3]); - return CopyAmbigious(AT_FDCWD, src, src, AT_FDCWD, dst, dst, flags) ? 0 : 1; + return CopyAmbigious(AT_FDCWD, src, src, AT_FDCWD, dst, dst, flags, + symbolic_dereference) ? 0 : 1; } if ( !target_directory ) @@ -529,7 +625,8 @@ int main(int argc, char* argv[]) { const char* src = argv[i]; const char* dst = target_directory; - if ( !CopyIntoDirectory(AT_FDCWD, src, src, AT_FDCWD, dst, dst, flags) ) + if ( !CopyIntoDirectory(AT_FDCWD, src, src, AT_FDCWD, dst, dst, flags, + symbolic_dereference) ) success = false; }