path patch

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@96 c046a42c-6fe2-441c-8c8c-71466251a162

3 files changed, 149 insertions, 14 deletions

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index c692ea371b..2974c01fe0 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -70,7 +70,6 @@ struct linux_binprm {
 	int fd;
         int e_uid, e_gid;
         int argc, envc;
-        char * interp_prefix;   /* prefix for interpreter */
         char * filename;        /* Name of binary */
         unsigned long loader, exec;
         int dont_iput;          /* binfmt handler has put inode */
@@ -756,8 +755,7 @@ static int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * r
 	     * is an a.out format binary
 	     */
 
-	    elf_interpreter = (char *)malloc(elf_ppnt->p_filesz+
-                                             strlen(bprm->interp_prefix));
+	    elf_interpreter = (char *)malloc(elf_ppnt->p_filesz);
 
 	    if (elf_interpreter == NULL) {
 		free (elf_phdata);
@@ -765,12 +763,9 @@ static int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * r
 		return -ENOMEM;
 	    }
 
-	    strcpy(elf_interpreter, bprm->interp_prefix);
 	    retval = lseek(bprm->fd, elf_ppnt->p_offset, SEEK_SET);
 	    if(retval >= 0) {
-		retval = read(bprm->fd, 
-			      elf_interpreter+strlen(bprm->interp_prefix), 
-			      elf_ppnt->p_filesz);
+		retval = read(bprm->fd, elf_interpreter, elf_ppnt->p_filesz);
 	    }
 	    if(retval < 0) {
 	 	perror("load_elf_binary2");
@@ -792,7 +787,7 @@ static int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * r
 	    printf("Using ELF interpreter %s\n", elf_interpreter);
 #endif
 	    if (retval >= 0) {
-		retval = open(elf_interpreter, O_RDONLY);
+		retval = open(path(elf_interpreter), O_RDONLY);
 		if(retval >= 0) {
 		    interpreter_fd = retval;
 		}
@@ -1060,8 +1055,7 @@ static int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * r
 
 
 
-int elf_exec(const char *interp_prefix, 
-             const char * filename, char ** argv, char ** envp, 
+int elf_exec(const char * filename, char ** argv, char ** envp, 
              struct target_pt_regs * regs, struct image_info *infop)
 {
         struct linux_binprm bprm;
@@ -1080,7 +1074,6 @@ int elf_exec(const char *interp_prefix,
 	else {
 	    bprm.fd = retval;
 	}
-        bprm.interp_prefix = (char *)interp_prefix;
         bprm.filename = (char *)filename;
         bprm.sh_bang = 0;
         bprm.loader = 0;
diff --git a/linux-user/path.c b/linux-user/path.c
new file mode 100644
index 0000000000..9e49076dc8
--- /dev/null
+++ b/linux-user/path.c
@@ -0,0 +1,142 @@
+/* Code to mangle pathnames into those matching a given prefix.
+   eg. open("/lib/foo.so") => open("/usr/gnemul/i386-linux/lib/foo.so");
+
+   The assumption is that this area does not change.
+*/
+#include <sys/types.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+#include "qemu.h"
+
+struct pathelem
+{
+    /* Name of this, eg. lib */
+    char *name;
+    /* Full path name, eg. /usr/gnemul/x86-linux/lib. */
+    char *pathname;
+    struct pathelem *parent;
+    /* Children */
+    unsigned int num_entries;
+    struct pathelem *entries[0];
+};
+
+static struct pathelem *base;
+
+/* First N chars of S1 match S2, and S2 is N chars long. */
+static int strneq(const char *s1, unsigned int n, const char *s2)
+{
+    unsigned int i;
+
+    for (i = 0; i < n; i++)
+	if (s1[i] != s2[i])
+	    return 0;
+    return s2[i] == 0;
+}
+
+static struct pathelem *add_entry(struct pathelem *root, const char *name);
+
+static struct pathelem *new_entry(const char *root,
+				  struct pathelem *parent,
+				  const char *name)
+{
+    struct pathelem *new = malloc(sizeof(*new));
+    new->name = strdup(name);
+    asprintf(&new->pathname, "%s/%s", root, name);
+    new->num_entries = 0;
+    return new;
+}
+
+#define streq(a,b) (strcmp((a), (b)) == 0)
+
+static struct pathelem *add_dir_maybe(struct pathelem *path)
+{
+    DIR *dir;
+
+    if ((dir = opendir(path->pathname)) != NULL) {
+	struct dirent *dirent;
+
+	while ((dirent = readdir(dir)) != NULL) {
+	    if (!streq(dirent->d_name,".") && !streq(dirent->d_name,"..")){
+		path = add_entry(path, dirent->d_name);
+	    }
+	}
+        closedir(dir);
+    }
+    return path;
+}
+
+static struct pathelem *add_entry(struct pathelem *root, const char *name)
+{
+    root->num_entries++;
+
+    root = realloc(root, sizeof(*root)
+		   + sizeof(root->entries[0])*root->num_entries);
+
+    root->entries[root->num_entries-1] = new_entry(root->pathname, root, name);
+    root->entries[root->num_entries-1]
+	= add_dir_maybe(root->entries[root->num_entries-1]);
+    return root;
+}
+
+/* This needs to be done after tree is stabalized (ie. no more reallocs!). */
+static void set_parents(struct pathelem *child, struct pathelem *parent)
+{
+    unsigned int i;
+
+    child->parent = parent;
+    for (i = 0; i < child->num_entries; i++)
+	set_parents(child->entries[i], child);
+}
+
+void init_paths(const char *prefix)
+{
+    if (prefix[0] != '/' ||
+        prefix[0] == '\0' ||
+        !strcmp(prefix, "/"))
+        return;
+
+    base = new_entry("", NULL, prefix+1);
+    base = add_dir_maybe(base);
+    set_parents(base, base);
+}
+
+/* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */
+static const char *
+follow_path(const struct pathelem *cursor, const char *name)
+{
+    unsigned int i, namelen;
+
+    name += strspn(name, "/");
+    namelen = strcspn(name, "/");
+
+    if (namelen == 0)
+	return cursor->pathname;
+
+    if (strneq(name, namelen, ".."))
+	return follow_path(cursor->parent, name + namelen);
+
+    if (strneq(name, namelen, "."))
+	return follow_path(cursor, name + namelen);
+
+    for (i = 0; i < cursor->num_entries; i++)
+	if (strneq(name, namelen, cursor->entries[i]->name))
+	    return follow_path(cursor->entries[i], name + namelen);
+
+    /* Not found */
+    return NULL;
+}
+
+/* Look for path in emulation dir, otherwise return name. */
+const char *path(const char *name)
+{
+    /* Only do absolute paths: quick and dirty, but should mostly be OK.
+       Could do relative by tracking cwd. */
+    if (!base || name[0] != '/')
+	return name;
+
+    return follow_path(base, name) ?: name;
+}
diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 882c3c039d..dddc7ad4c3 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -60,8 +60,7 @@ typedef struct TaskState {
 
 extern TaskState *first_task_state;
 
-int elf_exec(const char *interp_prefix, 
-             const char * filename, char ** argv, char ** envp, 
+int elf_exec(const char * filename, char ** argv, char ** envp, 
              struct target_pt_regs * regs, struct image_info *infop);
 
 void target_set_brk(char *new_brk);
@@ -75,5 +74,6 @@ void process_pending_signals(void *cpu_env);
 void signal_init(void);
 int queue_signal(int sig, target_siginfo_t *info);
 void save_v86_state(CPUX86State *env);
-
+void init_paths(const char *prefix);
+const char *path(const char *pathname);
 #endif