semihosting: Split out semihost_sys_lseek

Split out the non-ARM specific portions of SYS_SEEK to a
reusable function.  This handles all GuestFD.  Isolate the
curious ARM-specific return value processing to a new
callback, common_semi_seek_cb.

Expand the internal type of the offset to int64_t, and
provide the whence argument, which will be required by
m68k and nios2 semihosting.

Note that gdb_do_syscall %x reads target_ulong, not int.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 81 insertions, 0 deletions

diff --git a/semihosting/syscalls.c b/semihosting/syscalls.c
index eefbae74f1..9e3eb464b5 100644
--- a/semihosting/syscalls.c
+++ b/semihosting/syscalls.c
@@ -114,6 +114,13 @@ static void gdb_write(CPUState *cs, gdb_syscall_complete_cb complete,
                    (target_ulong)gf->hostfd, buf, len);
 }
 
+static void gdb_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
+                      GuestFD *gf, int64_t off, int gdb_whence)
+{
+    gdb_do_syscall(complete, "lseek,%x,%lx,%x",
+                   (target_ulong)gf->hostfd, off, (target_ulong)gdb_whence);
+}
+
 /*
  * Host semihosting syscall implementations.
  */
@@ -216,6 +223,29 @@ static void host_write(CPUState *cs, gdb_syscall_complete_cb complete,
     unlock_user(ptr, buf, 0);
 }
 
+static void host_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
+                       GuestFD *gf, int64_t off, int whence)
+{
+    /* So far, all hosts use the same values. */
+    QEMU_BUILD_BUG_ON(GDB_SEEK_SET != SEEK_SET);
+    QEMU_BUILD_BUG_ON(GDB_SEEK_CUR != SEEK_CUR);
+    QEMU_BUILD_BUG_ON(GDB_SEEK_END != SEEK_END);
+
+    off_t ret = off;
+    int err = 0;
+
+    if (ret == off) {
+        ret = lseek(gf->hostfd, ret, whence);
+        if (ret == -1) {
+            err = errno;
+        }
+    } else {
+        ret = -1;
+        err = EINVAL;
+    }
+    complete(cs, ret, err);
+}
+
 /*
  * Static file semihosting syscall implementations.
  */
@@ -241,6 +271,33 @@ static void staticfile_read(CPUState *cs, gdb_syscall_complete_cb complete,
     unlock_user(ptr, buf, len);
 }
 
+static void staticfile_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
+                             GuestFD *gf, int64_t off, int gdb_whence)
+{
+    int64_t ret;
+
+    switch (gdb_whence) {
+    case GDB_SEEK_SET:
+        ret = off;
+        break;
+    case GDB_SEEK_CUR:
+        ret = gf->staticfile.off + off;
+        break;
+    case GDB_SEEK_END:
+        ret = gf->staticfile.len + off;
+        break;
+    default:
+        ret = -1;
+        break;
+    }
+    if (ret >= 0 && ret <= gf->staticfile.len) {
+        gf->staticfile.off = ret;
+        complete(cs, ret, 0);
+    } else {
+        complete(cs, -1, EINVAL);
+    }
+}
+
 /*
  * Syscall entry points.
  */
@@ -356,3 +413,27 @@ void semihost_sys_write(CPUState *cs, gdb_syscall_complete_cb complete,
         complete(cs, -1, EBADF);
     }
 }
+
+void semihost_sys_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
+                        int fd, int64_t off, int gdb_whence)
+{
+    GuestFD *gf = get_guestfd(fd);
+
+    if (!gf) {
+        complete(cs, -1, EBADF);
+        return;
+    }
+    switch (gf->type) {
+    case GuestFDGDB:
+        gdb_lseek(cs, complete, gf, off, gdb_whence);
+        return;
+    case GuestFDHost:
+        host_lseek(cs, complete, gf, off, gdb_whence);
+        break;
+    case GuestFDStatic:
+        staticfile_lseek(cs, complete, gf, off, gdb_whence);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+}