Replace extended attributes with an NDBM-API-compatible database

zerocc2014 · Oct 29, 2017 · 63a9ff0 · 63a9ff0
1 parent a637c42
commit 63a9ff0
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Showing 12 changed files with 105 additions and 113 deletions.
diff --git a/app/AppDelegate.m b/app/AppDelegate.m
@@ -22,7 +22,7 @@ @implementation AppDelegate
 
 - (int)startThings {
     NSString *resourcePath = NSBundle.mainBundle.resourcePath;
-    int err = mount_root(resourcePath.UTF8String);
+    int err = mount_root(&realfs, resourcePath.UTF8String);
     if (err < 0)
         return err;
 

diff --git a/fs/fake.c b/fs/fake.c
@@ -0,0 +1,66 @@
+#include <ndbm.h>
+#include <string.h>
+#include <fcntl.h>
+#include "kernel/fs.h"
+
+struct ish_stat {
+    dword_t mode;
+    dword_t uid;
+    dword_t gid;
+    dword_t rdev;
+};
+
+static datum read_meta(struct mount *mount, const char *path, const char *type) {
+    DBM *db = mount->data;
+    if (db == NULL) {
+        char db_path[PATH_MAX];
+        strcpy(db_path, mount->source);
+        char *basename = strrchr(db_path, '/') + 1;
+        assert(strcmp(basename, "data") == 0);
+        strncpy(basename, "meta", 4);
+        db = dbm_open(db_path, O_RDWR, 0666);
+        assert(db != NULL);
+    }
+    char keydata[MAX_PATH+strlen(type)+1];
+    strcpy(keydata, type);
+    strcat(keydata, ":");
+    strcat(keydata, path);
+    datum key = {.dptr = keydata, .dsize = strlen(keydata)};
+    return dbm_fetch(db, key);
+}
+
+static int fakefs_stat(struct mount *mount, char *path, struct statbuf *fake_stat, bool follow_links) {
+    int err = realfs_stat(mount, path, fake_stat, follow_links);
+    if (err < 0)
+        return err;
+    datum d = read_meta(mount, path, "meta");
+    if (d.dptr != NULL) {
+        assert(d.dsize == sizeof(struct ish_stat));
+        struct ish_stat *ishstat = (void *) d.dptr;
+        fake_stat->mode = ishstat->mode;
+        fake_stat->uid = ishstat->uid;
+        fake_stat->gid = ishstat->gid;
+        fake_stat->rdev = ishstat->rdev;
+    }
+    return 0;
+}
+
+static int fakefs_fstat(struct fd *fd, struct statbuf *fake_stat) {
+    // this is truly sad, but there is no alternative
+    char path[MAX_PATH];
+    int err = fd->ops->getpath(fd, path);
+    if (err < 0)
+        return err;
+    return fakefs_stat(fd->mount, path, fake_stat, false);
+}
+
+const struct fs_ops fakefs = {
+    .open = realfs_open,
+    .unlink = realfs_unlink,
+    .stat = fakefs_stat,
+    .access = realfs_access,
+    .readlink = realfs_readlink,
+    .fstat = fakefs_fstat,
+    .statfs = realfs_statfs,
+    .flock = realfs_flock,
+};
diff --git a/fs/ishstat.h b/fs/ishstat.h
diff --git a/fs/real.c b/fs/real.c
@@ -14,7 +14,6 @@
 #include "kernel/fs.h"
 #include "fs/dev.h"
 #include "fs/tty.h"
-#include "fs/ishstat.h"
 
 static int getpath(int fd, char *buf) {
 #if defined(__linux__)
@@ -46,7 +45,7 @@ char *strnprepend(char *str, const char *prefix, size_t max) {
 
 // TODO translate goddamn flags
 
-static struct fd *realfs_open(struct mount *mount, char *path, int flags, int mode) {
+struct fd *realfs_open(struct mount *mount, char *path, int flags, int mode) {
     if (strnprepend(path, mount->source, MAX_PATH) == NULL)
         return ERR_PTR(_ENAMETOOLONG);
 
@@ -93,15 +92,7 @@ static void copy_stat(struct statbuf *fake_stat, struct stat *real_stat) {
     /* fake_stat->ctime_nsec = real_stat->st_ctim.tv_nsec; */
 }
 
-static void copy_xattr_stat(struct statbuf *fake_stat, struct xattr_stat *xstat) {
-    fake_stat->dev = xstat->dev;
-    fake_stat->mode = xstat->mode;
-    fake_stat->uid = xstat->uid;
-    fake_stat->gid = xstat->gid;
-    fake_stat->rdev = xstat->rdev;
-}
-
-static int realfs_stat(struct mount *mount, char *path, struct statbuf *fake_stat, bool follow_links) {
+int realfs_stat(struct mount *mount, char *path, struct statbuf *fake_stat, bool follow_links) {
     if (strnprepend(path, mount->source, MAX_PATH) == NULL)
         return _ENAMETOOLONG;
 
@@ -114,26 +105,18 @@ static int realfs_stat(struct mount *mount, char *path, struct statbuf *fake_sta
     if (stat_fn(path, &real_stat) < 0)
         return err_map(errno);
     copy_stat(fake_stat, &real_stat);
-
-    struct xattr_stat xstat;
-    if (lget_ishstat(path, &xstat) == sizeof(xstat))
-        copy_xattr_stat(fake_stat, &xstat);
     return 0;
 }
 
-static int realfs_fstat(struct fd *fd, struct statbuf *fake_stat) {
+int realfs_fstat(struct fd *fd, struct statbuf *fake_stat) {
     struct stat real_stat;
     if (fstat(fd->real_fd, &real_stat) < 0)
         return err_map(errno);
     copy_stat(fake_stat, &real_stat);
-
-    struct xattr_stat xstat;
-    if (fget_ishstat(fd->real_fd, &xstat) == sizeof(xstat))
-        copy_xattr_stat(fake_stat, &xstat);
     return 0;
 }
 
-static int realfs_unlink(struct mount *mount, char *path) {
+int realfs_unlink(struct mount *mount, char *path) {
     if (strnprepend(path, mount->source, MAX_PATH) == NULL)
         return _ENAMETOOLONG;
 
@@ -143,7 +126,7 @@ static int realfs_unlink(struct mount *mount, char *path) {
     return res;
 }
 
-static int realfs_access(struct mount *mount, char *path, int mode) {
+int realfs_access(struct mount *mount, char *path, int mode) {
     if (strnprepend(path, mount->source, MAX_PATH) == NULL)
         return _ENAMETOOLONG;
 
@@ -172,7 +155,7 @@ ssize_t realfs_write(struct fd *fd, const void *buf, size_t bufsize) {
     return res;
 }
 
-static int realfs_readdir(struct fd *fd, struct dir_entry *entry) {
+int realfs_readdir(struct fd *fd, struct dir_entry *entry) {
     if (fd->dir == NULL)
         fd->dir = fdopendir(fd->real_fd);
     if (fd->dir == NULL)
@@ -191,7 +174,7 @@ static int realfs_readdir(struct fd *fd, struct dir_entry *entry) {
     return 0;
 }
 
-static off_t realfs_lseek(struct fd *fd, off_t offset, int whence) {
+off_t realfs_lseek(struct fd *fd, off_t offset, int whence) {
     if (whence == LSEEK_SET)
         whence = SEEK_SET;
     else if (whence == LSEEK_CUR)
@@ -206,7 +189,7 @@ static off_t realfs_lseek(struct fd *fd, off_t offset, int whence) {
     return res;
 }
 
-static int realfs_mmap(struct fd *fd, off_t offset, size_t len, int prot, int flags, void **mem_out) {
+int realfs_mmap(struct fd *fd, off_t offset, size_t len, int prot, int flags, void **mem_out) {
     int mmap_flags = 0;
     if (flags & MMAP_PRIVATE) mmap_flags |= MAP_PRIVATE;
     if (flags & MMAP_SHARED) mmap_flags |= MAP_SHARED;
@@ -218,7 +201,7 @@ static int realfs_mmap(struct fd *fd, off_t offset, size_t len, int prot, int fl
     return 0;
 }
 
-static ssize_t realfs_readlink(struct mount *mount, char *path, char *buf, size_t bufsize) {
+ssize_t realfs_readlink(struct mount *mount, char *path, char *buf, size_t bufsize) {
     if (strnprepend(path, mount->source, MAX_PATH) == NULL)
         return _ENAMETOOLONG;
 
@@ -228,7 +211,7 @@ static ssize_t realfs_readlink(struct mount *mount, char *path, char *buf, size_
     return size;
 }
 
-static int realfs_getpath(struct fd *fd, char *buf) {
+int realfs_getpath(struct fd *fd, char *buf) {
     int err = getpath(fd->real_fd, buf);
     if (err < 0)
         return err;
@@ -241,14 +224,14 @@ static int realfs_getpath(struct fd *fd, char *buf) {
     return 0;
 }
 
-static int realfs_statfs(struct mount *mount, struct statfsbuf *stat) {
+int realfs_statfs(struct mount *mount, struct statfsbuf *stat) {
     stat->type = 0x7265616c;
     stat->namelen = NAME_MAX;
     stat->bsize = PAGE_SIZE;
     return 0;
 }
 
-static int realfs_flock(struct fd *fd, int operation) {
+int realfs_flock(struct fd *fd, int operation) {
     int real_op = 0;
     if (operation & LOCK_SH_) real_op |= LOCK_SH;
     if (operation & LOCK_EX_) real_op |= LOCK_EX;

diff --git a/kernel/fs.h b/kernel/fs.h
@@ -65,6 +65,7 @@ struct mount {
     const char *source;
     const struct fs_ops *fs;
     struct mount *next;
+    void *data;
 };
 extern struct mount *mounts;
 
@@ -180,6 +181,15 @@ int path_normalize(struct fd *at, const char *path, char *out, bool follow_links
 
 // real fs
 extern const struct fs_ops realfs;
+
+struct fd *realfs_open(struct mount *mount, char *path, int flags, int mode);
+int realfs_stat(struct mount *mount, char *path, struct statbuf *fake_stat, bool follow_links);
+int realfs_fstat(struct fd *fd, struct statbuf *fake_stat);
+int realfs_unlink(struct mount *mount, char *path);
+int realfs_access(struct mount *mount, char *path, int mode);
+ssize_t realfs_readlink(struct mount *mount, char *path, char *buf, size_t bufsize);
+int realfs_statfs(struct mount *mount, struct statfsbuf *stat);
+int realfs_flock(struct fd *fd, int operation);
 extern const struct fd_ops realfs_fdops;
 ssize_t realfs_read(struct fd *fd, void *buf, size_t bufsize);
 ssize_t realfs_write(struct fd *fd, const void *buf, size_t bufsize);
@@ -188,6 +198,9 @@ int realfs_close(struct fd *fd);
 // adhoc fs
 struct fd *adhoc_fd_create(void);
 
+// fake fs
+extern const struct fs_ops fakefs;
+
 // TODO put this somewhere else
 char *strnprepend(char *str, const char *prefix, size_t max);
 

diff --git a/kernel/init.c b/kernel/init.c
@@ -5,14 +5,14 @@
 #include "kernel/calls.h"
 #include "fs/tty.h"
 
-int mount_root(const char *source) {
+int mount_root(const struct fs_ops *fs, const char *source) {
     char source_realpath[MAX_PATH + 1];
     if (realpath(source, source_realpath) == NULL)
         return err_map(errno);
     mounts = malloc(sizeof(struct mount));
     mounts->point = "";
     mounts->source = strdup(source_realpath);
-    mounts->fs = &realfs;
+    mounts->fs = fs;
     mounts->next = NULL;
     return 0;
 }

diff --git a/kernel/init.h b/kernel/init.h
@@ -3,7 +3,7 @@
 
 #include "fs/tty.h"
 
-int mount_root(const char *source);
+int mount_root(const struct fs_ops *fs, const char *source);
 int create_init_process(const char *program, char *const argv[], char *const envp[]);
 int create_stdio(struct tty_driver driver);
 

diff --git a/meson.build b/meson.build
@@ -53,6 +53,7 @@ src = [
     'fs/generic.c',
     'fs/path.c',
     'fs/real.c',
+    'fs/fake.c',
     'fs/poll.c',
     'fs/adhoc.c',
 
@@ -71,21 +72,23 @@ src = [
     cified_vdso,
 ]
 
+cc = meson.get_compiler('c')
 threads = dependency('threads')
-librt = meson.get_compiler('c').find_library('rt', required: false)
+librt = cc.find_library('rt', required: false)
 softfloat = subproject('softfloat').get_variable('softfloat_dep')
+dbm = [cc.find_library('gdbm', required: false), cc.find_library('gdbm_compat', required: false)]
 
 libish = library('ish', src,
     include_directories: includes,
-    dependencies: [librt, threads, softfloat])
+    dependencies: [librt, threads, softfloat, dbm])
 ish = declare_dependency(
     link_with: libish,
     include_directories: includes)
 
 # ptraceomatic et al
 subdir('tools')
 
-executable('ish', ['main.c'], dependencies: [ish, softfloat, threads])
+executable('ish', ['main.c'], dependencies: [ish, softfloat, threads, dbm])
 
 gdb_scripts = ['ish-gdb.gdb']
 foreach script : gdb_scripts

diff --git a/tools/meson.build b/tools/meson.build
@@ -5,13 +5,12 @@ if build_machine.system() == 'linux'
         'ptutil.c',
         cified_vdso,
     ]
-    executable('ptraceomatic', ['ptraceomatic.c', 'undefined-flags.c', transplant_src], dependencies: [ish, softfloat, threads])
+    executable('ptraceomatic', ['ptraceomatic.c', 'undefined-flags.c', transplant_src],
+        dependencies: [ish, softfloat, threads, dbm])
     configure_file(input: 'ptraceomatic-gdb.gdb', output: '@PLAINNAME@', configuration: configuration_data())
 
     # tools for messing with vdsos
     # executable('vdso-dump', ['vdso-dump.c'], c_args: ['-m32'], link_args: ['-m32'])
     executable('vdso-transplant', ['vdso-transplant-main.c', transplant_src],
         include_directories: includes)
 endif
-
-executable('xattrify_fs', ['xattrify_fs.c'], include_directories: includes)
diff --git a/tools/ptraceomatic.c b/tools/ptraceomatic.c
@@ -315,7 +315,7 @@ static void step_tracing(struct cpu_state *cpu, int pid, int sender, int receive
             case 145: { // readv
                 struct io_vec vecs[regs.rdx];
                 (void) user_get(regs.rcx, vecs);
-                for (int i = 0; i < regs.rdx; i++)
+                for (unsigned i = 0; i < regs.rdx; i++)
                     pt_copy(pid, vecs[i].base, vecs[i].len);
                 break;
             }