diff options
Diffstat (limited to 'src/skaembutils/s6-update-symlinks.c')
| -rw-r--r-- | src/skaembutils/s6-update-symlinks.c | 367 |
1 files changed, 367 insertions, 0 deletions
diff --git a/src/skaembutils/s6-update-symlinks.c b/src/skaembutils/s6-update-symlinks.c new file mode 100644 index 0000000..ba89b06 --- /dev/null +++ b/src/skaembutils/s6-update-symlinks.c @@ -0,0 +1,367 @@ +/* ISC license. */ + +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> +#include <errno.h> +#include <stdio.h> +#include <skalibs/bytestr.h> +#include <skalibs/direntry.h> +#include <skalibs/strerr2.h> +#include <skalibs/stralloc.h> +#include <skalibs/djbunix.h> +#include <skalibs/random.h> + +#define USAGE "s6-update-symlinks /destdir /srcdir [ /srcdir ... ]" + +#define MAGICNEW ":s6-update-symlinks-new" +#define MAGICOLD ":s6-update-symlinks-old" + +#define CONFLICT -2 +#define ERROR -1 +#define MODIFIED 0 +#define OVERRIDEN 1 + +static stralloc errdst = STRALLOC_ZERO ; +static stralloc errsrc = STRALLOC_ZERO ; + + +typedef struct stralloc3 stralloc3, *stralloc3_ref ; +struct stralloc3 +{ + stralloc dst ; + stralloc src ; + stralloc tmp ; +} ; + +#define STRALLOC3_ZERO { STRALLOC_ZERO, STRALLOC_ZERO, STRALLOC_ZERO } + + +static void cleanup (stralloc *sa, unsigned int pos) +{ + register int e = errno ; + rm_rf_in_tmp(sa, pos) ; + errno = e ; +} + + +static int makeuniquename (stralloc *sa, char const *path, char const *magic) +{ + unsigned int base = sa->len ; + int wasnull = !sa->s ; + if (!stralloc_cats(sa, path)) return 0 ; + if (!stralloc_cats(sa, magic)) goto err ; + if (random_sauniquename(sa, 8) == -1) goto err ; + if (!stralloc_0(sa)) goto err ; + return 1 ; + +err: + if (wasnull) stralloc_free(sa) ; else sa->len = base ; + return 0 ; +} + + +static int addlink (stralloc3 *blah, unsigned int dstpos, unsigned int srcpos) +{ + if (symlink(blah->src.s + srcpos, blah->dst.s + dstpos) >= 0) return MODIFIED ; + if (errno != EEXIST) return ERROR ; + + { + unsigned int dstbase = blah->dst.len ; + unsigned int srcbase = blah->src.len ; + unsigned int tmpbase = blah->tmp.len ; + unsigned int dststop ; + unsigned int srcstop ; + signed int diffsize = 0 ; + int collect = 1 ; + + { + register unsigned int n = str_len(blah->dst.s + dstpos) ; + if (!stralloc_readyplus(&blah->dst, n+1)) return ERROR ; + stralloc_catb(&blah->dst, blah->dst.s + dstpos, n) ; + } + stralloc_catb(&blah->dst, "/", 1) ; + dststop = blah->dst.len ; + + { + int r ; + DIR *dir = opendir(blah->dst.s + dstpos) ; + if (!dir) + { + blah->dst.len = dstbase ; + if (errno != ENOTDIR) return ERROR ; + if ((unlink(blah->dst.s + dstpos) == -1) + || (symlink(blah->src.s + srcpos, blah->dst.s + dstpos) == -1)) + return ERROR ; + return OVERRIDEN ; /* replaced a link to a normal file */ + } + r = sareadlink(&blah->src, blah->dst.s + dstpos) ; + if ((r == -1) && (errno != EINVAL)) + { + register int e = errno ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + if (r < 0) + { + for (;;) + { + register direntry *d ; + errno = 0 ; + d = readdir(dir) ; + if (!d) break ; + if ((d->d_name[0] == '.') && (!d->d_name[1] || ((d->d_name[1] == '.') && !d->d_name[2]))) + continue ; + diffsize-- ; /* need to know the size for collect */ + } + if (errno) + { + register int e = errno ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + } + else if ((unlink(blah->dst.s + dstpos) == -1) + || (mkdir(blah->dst.s + dstpos, 0777) == -1) + || !stralloc_catb(&blah->src, "/", 1)) + { + register int e = errno ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + else /* expand */ + { + srcstop = blah->src.len ; + for (;;) + { + register direntry *d ; + errno = 0 ; + d = readdir(dir) ; + if (!d) break ; + if ((d->d_name[0] == '.') && (!d->d_name[1] || ((d->d_name[1] == '.') && !d->d_name[2]))) + continue ; + diffsize-- ; + blah->dst.len = dststop ; + blah->src.len = srcstop ; + if (!stralloc_cats(&blah->dst, d->d_name) || !stralloc_0(&blah->dst) + || !stralloc_cats(&blah->src, d->d_name) || !stralloc_0(&blah->src) + || (symlink(blah->src.s + srcbase, blah->dst.s + dstbase) == -1)) + { + register int e = errno ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + } + if (errno) + { + register int e = errno ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + } + dir_close(dir) ; + } + + blah->src.len = srcbase ; + { + register unsigned int n = str_len(blah->src.s + srcpos) ; + if (!stralloc_readyplus(&blah->src, n+1)) + { + blah->dst.len = dstbase ; + return ERROR ; + } + stralloc_catb(&blah->src, blah->src.s + srcpos, n) ; + } + stralloc_catb(&blah->src, "/", 1) ; + srcstop = blah->src.len ; + + + /* prepare tmp for recursion */ + + { + DIR *dir = opendir(blah->src.s + srcpos) ; + if (!dir) + { + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + if (errno != ENOTDIR) return ERROR ; + errdst.len = errsrc.len = 0 ; + if (!stralloc_cats(&errdst, blah->dst.s + dstpos) || !stralloc_0(&errdst) + || !stralloc_cats(&errsrc, blah->src.s + srcpos) || !stralloc_0(&errsrc)) + return ERROR ; + return CONFLICT ; /* dst is a dir but src is not */ + } + for (;;) + { + register direntry *d ; + errno = 0 ; + d = readdir(dir) ; + if (!d) break ; + if ((d->d_name[0] == '.') && (!d->d_name[1] || ((d->d_name[1] == '.') && !d->d_name[2]))) + continue ; + if (!stralloc_cats(&blah->tmp, d->d_name) || !stralloc_0(&blah->tmp)) + { + register int e = errno ; + blah->tmp.len = tmpbase ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + } + if (errno) + { + register int e = errno ; + blah->tmp.len = tmpbase ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + dir_close(dir) ; + errno = e ; + return ERROR ; + } + dir_close(dir) ; + } + + + /* recurse */ + + { + unsigned int i = tmpbase ; + while (i < blah->tmp.len) + { + diffsize++ ; + blah->dst.len = dststop ; + blah->src.len = srcstop ; + { + register unsigned int n = str_len(blah->tmp.s + i) + 1 ; + if (!stralloc_catb(&blah->dst, blah->tmp.s + i, n) + || !stralloc_catb(&blah->src, blah->tmp.s + i, n)) + { + blah->tmp.len = tmpbase ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + return ERROR ; + } + i += n ; + } + switch (addlink(blah, dstbase, srcbase)) + { + case ERROR : + blah->tmp.len = tmpbase ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + return ERROR ; + case CONFLICT : + blah->tmp.len = tmpbase ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + return CONFLICT ; + case MODIFIED : + collect = 0 ; + } + } + } + blah->tmp.len = tmpbase ; + blah->src.len = srcbase ; + blah->dst.len = dstbase ; + + + /* collect */ + + if (collect && !diffsize) + { + if (rm_rf_in_tmp(&blah->dst, dstpos) == -1) return ERROR ; + if (symlink(blah->src.s + srcpos, blah->dst.s + dstpos) == -1) return ERROR ; + return OVERRIDEN ; + } + } + return MODIFIED ; +} + +int main (int argc, char *const *argv) +{ + stralloc3 blah = STRALLOC3_ZERO ; + PROG = "s6-update-symlinks" ; + if (argc < 3) strerr_dieusage(100, USAGE) ; + { + register char *const *p = argv + 1 ; + for (; *p ; p++) if (**p != '/') strerr_dieusage(100, USAGE) ; + } + { + register unsigned int i = str_len(argv[1]) ; + while (i && (argv[1][i-1] == '/')) argv[1][--i] = 0 ; + if (!i) strerr_diefu1x(100, "replace root directory") ; + } + if (!makeuniquename(&blah.dst, argv[1], MAGICNEW)) + strerr_diefu2sys(111, "make random unique name based on ", argv[1]) ; + if ((unlink(blah.dst.s) == -1) && (errno != ENOENT)) + strerr_diefu2sys(111, "unlink ", blah.dst.s) ; + + { + char *const *p = argv + 2 ; + for (; *p ; p++) + { + register int r ; + blah.src.len = 0 ; + if (!stralloc_cats(&blah.src, *p) || !stralloc_0(&blah.src)) + strerr_diefu1sys(111, "make stralloc") ; + r = addlink(&blah, 0, 0) ; + if (r < 0) + { + stralloc_free(&blah.tmp) ; + stralloc_free(&blah.src) ; + cleanup(&blah.dst, 0) ; + stralloc_free(&blah.dst) ; + if (r == CONFLICT) + strerr_dief4x(100, "destination ", errdst.s, " conflicts with source ", errsrc.s) ; + else + strerr_dief2sys(111, "error processing ", *p) ; + } + } + } + stralloc_free(&blah.tmp) ; + + if (rename(blah.dst.s, argv[1]) == -1) /* be atomic if possible */ + { + blah.src.len = 0 ; + if (!makeuniquename(&blah.src, argv[1], MAGICOLD)) + { + cleanup(&blah.dst, 0) ; + strerr_diefu2sys(111, "make random unique name based on ", argv[1]) ; + } + + if (rename(argv[1], blah.src.s) == -1) + { + cleanup(&blah.dst, 0) ; + strerr_diefu4sys(111, "rename ", argv[1], " to ", blah.src.s) ; + } + /* XXX: unavoidable race condition here: argv[1] does not exist */ + if (rename(blah.dst.s, argv[1]) == -1) + { + rename(blah.src.s, argv[1]) ; + cleanup(&blah.dst, 0) ; + strerr_diefu4sys(111, "rename ", blah.dst.s, " to ", argv[1]) ; + } + stralloc_free(&blah.dst) ; + if (rm_rf_in_tmp(&blah.src, 0) == -1) + strerr_warnwu2sys("remove old directory ", blah.src.s) ; + stralloc_free(&blah.src) ; + } + + return 0 ; +} |