Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 214 insertions, 0 deletions

diff --git a/bsd-user/bsdload.c b/bsd-user/bsdload.c
new file mode 100644
index 000000000..5b3c061a4
--- /dev/null
+++ b/bsd-user/bsdload.c
@@ -0,0 +1,214 @@
+/*
+ *  Load BSD executables.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+
+#include "qemu.h"
+
+/* ??? This should really be somewhere else.  */
+abi_long memcpy_to_target(abi_ulong dest, const void *src,
+                          unsigned long len)
+{
+    void *host_ptr;
+
+    host_ptr = lock_user(VERIFY_WRITE, dest, len, 0);
+    if (!host_ptr) {
+        return -TARGET_EFAULT;
+    }
+    memcpy(host_ptr, src, len);
+    unlock_user(host_ptr, dest, 1);
+    return 0;
+}
+
+static int count(char **vec)
+{
+    int         i;
+
+    for (i = 0; *vec; i++) {
+        vec++;
+    }
+
+    return i;
+}
+
+static int prepare_binprm(struct bsd_binprm *bprm)
+{
+    struct stat         st;
+    int mode;
+    int retval;
+
+    if (fstat(bprm->fd, &st) < 0) {
+        return -errno;
+    }
+
+    mode = st.st_mode;
+    if (!S_ISREG(mode)) {        /* Must be regular file */
+        return -EACCES;
+    }
+    if (!(mode & 0111)) {        /* Must have at least one execute bit set */
+        return -EACCES;
+    }
+
+    bprm->e_uid = geteuid();
+    bprm->e_gid = getegid();
+
+    /* Set-uid? */
+    if (mode & S_ISUID) {
+        bprm->e_uid = st.st_uid;
+    }
+
+    /* Set-gid? */
+    /*
+     * If setgid is set but no group execute bit then this
+     * is a candidate for mandatory locking, not a setgid
+     * executable.
+     */
+    if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+        bprm->e_gid = st.st_gid;
+    }
+
+    memset(bprm->buf, 0, sizeof(bprm->buf));
+    retval = lseek(bprm->fd, 0L, SEEK_SET);
+    if (retval >= 0) {
+        retval = read(bprm->fd, bprm->buf, 128);
+    }
+    if (retval < 0) {
+        perror("prepare_binprm");
+        exit(-1);
+    } else {
+        return retval;
+    }
+}
+
+/* Construct the envp and argv tables on the target stack.  */
+abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp,
+                              abi_ulong stringp)
+{
+    int n = sizeof(abi_ulong);
+    abi_ulong envp;
+    abi_ulong argv;
+
+    sp -= (envc + 1) * n;
+    envp = sp;
+    sp -= (argc + 1) * n;
+    argv = sp;
+    sp -= n;
+    /* FIXME - handle put_user() failures */
+    put_user_ual(argc, sp);
+
+    while (argc-- > 0) {
+        /* FIXME - handle put_user() failures */
+        put_user_ual(stringp, argv);
+        argv += n;
+        stringp += target_strlen(stringp) + 1;
+    }
+    /* FIXME - handle put_user() failures */
+    put_user_ual(0, argv);
+    while (envc-- > 0) {
+        /* FIXME - handle put_user() failures */
+        put_user_ual(stringp, envp);
+        envp += n;
+        stringp += target_strlen(stringp) + 1;
+    }
+    /* FIXME - handle put_user() failures */
+    put_user_ual(0, envp);
+
+    return sp;
+}
+
+static bool is_there(const char *candidate)
+{
+    struct stat fin;
+
+    /* XXX work around access(2) false positives for superuser */
+    if (access(candidate, X_OK) == 0 && stat(candidate, &fin) == 0 &&
+            S_ISREG(fin.st_mode) && (getuid() != 0 ||
+                (fin.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0)) {
+        return true;
+    }
+
+    return false;
+}
+
+int loader_exec(const char *filename, char **argv, char **envp,
+                struct target_pt_regs *regs, struct image_info *infop,
+                struct bsd_binprm *bprm)
+{
+    char *path, fullpath[PATH_MAX];
+    int retval, i;
+
+    bprm->p = TARGET_PAGE_SIZE * MAX_ARG_PAGES;
+    for (i = 0; i < MAX_ARG_PAGES; i++) {       /* clear page-table */
+        bprm->page[i] = NULL;
+    }
+
+    if (strchr(filename, '/') != NULL) {
+        path = realpath(filename, fullpath);
+        if (path == NULL) {
+            /* Failed to resolve. */
+            return -1;
+        }
+        if (!is_there(path)) {
+            return -1;
+        }
+    } else {
+        path = g_find_program_in_path(filename);
+        if (path == NULL) {
+            return -1;
+        }
+    }
+
+    retval = open(path, O_RDONLY);
+    if (retval < 0) {
+        g_free(path);
+        return retval;
+    }
+
+    bprm->fullpath = path;
+    bprm->fd = retval;
+    bprm->filename = (char *)filename;
+    bprm->argc = count(argv);
+    bprm->argv = argv;
+    bprm->envc = count(envp);
+    bprm->envp = envp;
+
+    retval = prepare_binprm(bprm);
+
+    if (retval >= 0) {
+        if (bprm->buf[0] == 0x7f
+                && bprm->buf[1] == 'E'
+                && bprm->buf[2] == 'L'
+                && bprm->buf[3] == 'F') {
+            retval = load_elf_binary(bprm, regs, infop);
+        } else {
+            fprintf(stderr, "Unknown binary format\n");
+            return -1;
+        }
+    }
+
+    if (retval >= 0) {
+        /* success.  Initialize important registers */
+        do_init_thread(regs, infop);
+        return retval;
+    }
+
+    /* Something went wrong, return the inode and free the argument pages*/
+    for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
+        g_free(bprm->page[i]);
+    }
+    return retval;
+}