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linux-user: Expose do_guest_openat() and do_guest_readlink()

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These functions will be required by the GDB stub in order to provide
the guest view of /proc to GDB.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230621203627.1808446-2-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-32-alex.bennee@linaro.org>
This commit is contained in:
Ilya Leoshkevich 2023-06-30 19:04:16 +01:00 • committed by Alex Bennée
parent 2261b73c28
commit a4dab0a0d3
2 changed files with 38 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

3
linux-user/qemu.h
View file

@ -165,6 +165,9 @@ typedef struct TaskState {
} TaskState; } TaskState;
abi_long do_brk(abi_ulong new_brk); abi_long do_brk(abi_ulong new_brk);
int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname,
int flags, mode_t mode);
ssize_t do_guest_readlink(const char *pathname, char *buf, size_t bufsiz);
/* user access */ /* user access */

54
linux-user/syscall.c
View file

@ -8448,7 +8448,8 @@ static int open_hardware(CPUArchState *cpu_env, int fd)
} }
#endif #endif
static int do_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, int flags, mode_t mode) int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname,
int flags, mode_t mode)
{ {
struct fake_open { struct fake_open {
const char *filename; const char *filename;
@ -8520,6 +8521,36 @@ static int do_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, int
return safe_openat(dirfd, path(pathname), flags, mode); return safe_openat(dirfd, path(pathname), flags, mode);
} }
ssize_t do_guest_readlink(const char *pathname, char *buf, size_t bufsiz)
{
ssize_t ret;
if (!pathname || !buf) {
errno = EFAULT;
return -1;
}
if (!bufsiz) {
/* Short circuit this for the magic exe check. */
errno = EINVAL;
return -1;
}
if (is_proc_myself((const char *)pathname, "exe")) {
/*
* Don't worry about sign mismatch as earlier mapping
* logic would have thrown a bad address error.
*/
ret = MIN(strlen(exec_path), bufsiz);
/* We cannot NUL terminate the string. */
memcpy(buf, exec_path, ret);
} else {
ret = readlink(path(pathname), buf, bufsiz);
}
return ret;
}
static int do_execveat(CPUArchState *cpu_env, int dirfd, static int do_execveat(CPUArchState *cpu_env, int dirfd,
abi_long pathname, abi_long guest_argp, abi_long pathname, abi_long guest_argp,
abi_long guest_envp, int flags) abi_long guest_envp, int flags)
@ -8994,7 +9025,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
case TARGET_NR_open: case TARGET_NR_open:
if (!(p = lock_user_string(arg1))) if (!(p = lock_user_string(arg1)))
return -TARGET_EFAULT; return -TARGET_EFAULT;
ret = get_errno(do_openat(cpu_env, AT_FDCWD, p, ret = get_errno(do_guest_openat(cpu_env, AT_FDCWD, p,
target_to_host_bitmask(arg2, fcntl_flags_tbl), target_to_host_bitmask(arg2, fcntl_flags_tbl),
arg3)); arg3));
fd_trans_unregister(ret); fd_trans_unregister(ret);
@ -9004,7 +9035,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
case TARGET_NR_openat: case TARGET_NR_openat:
if (!(p = lock_user_string(arg2))) if (!(p = lock_user_string(arg2)))
return -TARGET_EFAULT; return -TARGET_EFAULT;
ret = get_errno(do_openat(cpu_env, arg1, p, ret = get_errno(do_guest_openat(cpu_env, arg1, p,
target_to_host_bitmask(arg3, fcntl_flags_tbl), target_to_host_bitmask(arg3, fcntl_flags_tbl),
arg4)); arg4));
fd_trans_unregister(ret); fd_trans_unregister(ret);
@ -10229,22 +10260,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
void *p2; void *p2;
p = lock_user_string(arg1); p = lock_user_string(arg1);
p2 = lock_user(VERIFY_WRITE, arg2, arg3, 0); p2 = lock_user(VERIFY_WRITE, arg2, arg3, 0);
if (!p || !p2) { ret = get_errno(do_guest_readlink(p, p2, arg3));
ret = -TARGET_EFAULT;
} else if (!arg3) {
/* Short circuit this for the magic exe check. */
ret = -TARGET_EINVAL;
} else if (is_proc_myself((const char *)p, "exe")) {
/*
* Don't worry about sign mismatch as earlier mapping
* logic would have thrown a bad address error.
*/
ret = MIN(strlen(exec_path), arg3);
/* We cannot NUL terminate the string. */
memcpy(p2, exec_path, ret);
} else {
ret = get_errno(readlink(path(p), p2, arg3));
}
unlock_user(p2, arg2, ret); unlock_user(p2, arg2, ret);
unlock_user(p, arg1, 0); unlock_user(p, arg1, 0);
} }