semihosting: fix handling of errno

This patch fixes the handling of errno by setting the sys_errn
only if error has actually occurred during the semihosting call.
It also fixes few issues where error was not set in the first place.

Change-Id: I2fbe562f3ec5e6220b800de04cd33aa1f409c7a0
Signed-off-by: Marek Vrbka <[email protected]>
Reviewed-on: https://review.openocd.org/c/openocd/+/7730
Tested-by: jenkins
Reviewed-by: Antonio Borneo <[email protected]>
Reviewed-by: Jan Matyas <[email protected]>

src/target/semihosting_common.c

@@ -223,7 +223,10 @@ static ssize_t semihosting_write(struct semihosting *semihosting, int fd, void *
  return semihosting_redirect_write(semihosting, buf, size);
 
  /* default write */
- return write(fd, buf, size);
+ int result = write(fd, buf, size);
+ if (result == -1)
+ semihosting->sys_errno = errno;
+ return result;
 }
 
 static ssize_t semihosting_redirect_read(struct semihosting *semihosting, void *buf, int size)
@@ -268,7 +271,8 @@ static inline ssize_t semihosting_read(struct semihosting *semihosting, int fd,
 
  /* default read */
  ssize_t result = read(fd, buf, size);
- semihosting->sys_errno = errno;
+ if (result == -1)
+ semihosting->sys_errno = errno;
 
  return result;
 }
@@ -449,12 +453,7 @@ int semihosting_common(struct target *target)
  (fd == 0) ? "stdin" :
  (fd == 1) ? "stdout" : "stderr");
  /* Just pretend success */
- if (semihosting->is_fileio) {
- semihosting->result = 0;
- } else {
- semihosting->result = 0;
- semihosting->sys_errno = 0;
- }
+ semihosting->result = 0;
  break;
  }
  /* Close the descriptor */
@@ -464,7 +463,8 @@ int semihosting_common(struct target *target)
  fileio_info->param_1 = fd;
  } else {
  semihosting->result = close(fd);
- semihosting->sys_errno = errno;
+ if (semihosting->result == -1)
+ semihosting->sys_errno = errno;
  LOG_DEBUG("close(%d)=%" PRId64, fd, semihosting->result);
  }
  }
@@ -842,7 +842,8 @@ int semihosting_common(struct target *target)
  int fd = semihosting_get_field(target, 0, fields);
  // isatty() on Windows may return any non-zero value if fd is a terminal
  semihosting->result = isatty(fd) ? 1 : 0;
- semihosting->sys_errno = errno;
+ if (semihosting->result == 0)
+ semihosting->sys_errno = errno;
  LOG_DEBUG("isatty(%d)=%" PRId64, fd, semihosting->result);
  }
  break;
@@ -934,14 +935,16 @@ int semihosting_common(struct target *target)
  semihosting->result = -1;
  semihosting->sys_errno = EINVAL;
  } else if (strcmp((char *)fn, ":tt") == 0) {
- if (mode == 0)
+ if (mode == 0) {
  semihosting->result = 0;
- else if (mode == 4)
+ } else if (mode == 4) {
  semihosting->result = 1;
- else if (mode == 8)
+ } else if (mode == 8) {
  semihosting->result = 2;
- else
+ } else {
  semihosting->result = -1;
+ semihosting->sys_errno = EINVAL;
+ }
  } else {
  semihosting->hit_fileio = true;
  fileio_info->identifier = "open";
@@ -956,33 +959,32 @@ int semihosting_common(struct target *target)
  * - 0-3 ("r") for stdin,
  * - 4-7 ("w") for stdout,
  * - 8-11 ("a") for stderr */
+ int fd;
  if (mode < 4) {
- int fd = dup(STDIN_FILENO);
- semihosting->result = fd;
+ fd = dup(STDIN_FILENO);
  semihosting->stdin_fd = fd;
- semihosting->sys_errno = errno;
- LOG_DEBUG("dup(STDIN)=%" PRId64, semihosting->result);
+ LOG_DEBUG("dup(STDIN)=%d", fd);
  } else if (mode < 8) {
- int fd = dup(STDOUT_FILENO);
- semihosting->result = fd;
+ fd = dup(STDOUT_FILENO);
  semihosting->stdout_fd = fd;
- semihosting->sys_errno = errno;
- LOG_DEBUG("dup(STDOUT)=%" PRId64, semihosting->result);
+ LOG_DEBUG("dup(STDOUT)=%d", fd);
  } else {
- int fd = dup(STDERR_FILENO);
- semihosting->result = fd;
+ fd = dup(STDERR_FILENO);
  semihosting->stderr_fd = fd;
- semihosting->sys_errno = errno;
- LOG_DEBUG("dup(STDERR)=%" PRId64, semihosting->result);
+ LOG_DEBUG("dup(STDERR)=%d", fd);
  }
+ semihosting->result = fd;
+ if (fd == -1)
+ semihosting->sys_errno = errno;
  } else {
  /* cygwin requires the permission setting
  * otherwise it will fail to reopen a previously
  * written file */
  semihosting->result = open((char *)fn,
  open_host_modeflags[mode],
  0644);
- semihosting->sys_errno = errno;
+ if (semihosting->result == -1)
+ semihosting->sys_errno = errno;
  LOG_DEBUG("open('%s')=%" PRId64, fn, semihosting->result);
  }
  }
@@ -1131,7 +1133,8 @@ int semihosting_common(struct target *target)
  }
  fn[len] = 0;
  semihosting->result = remove((char *)fn);
- semihosting->sys_errno = errno;
+ if (semihosting->result == -1)
+ semihosting->sys_errno = errno;
  LOG_DEBUG("remove('%s')=%" PRId64, fn, semihosting->result);
 
  free(fn);
@@ -1200,7 +1203,9 @@ int semihosting_common(struct target *target)
  fn2[len2] = 0;
  semihosting->result = rename((char *)fn1,
  (char *)fn2);
- semihosting->sys_errno = errno;
+ // rename() on Windows returns nonzero on error
+ if (semihosting->result != 0)
+ semihosting->sys_errno = errno;
  LOG_DEBUG("rename('%s', '%s')=%" PRId64 " %d", fn1, fn2, semihosting->result, errno);
  free(fn1);
  free(fn2);
@@ -1245,7 +1250,8 @@ int semihosting_common(struct target *target)
  fileio_info->param_3 = SEEK_SET;
  } else {
  semihosting->result = lseek(fd, pos, SEEK_SET);
- semihosting->sys_errno = errno;
+ if (semihosting->result == -1)
+ semihosting->sys_errno = errno;
  LOG_DEBUG("lseek(%d, %d)=%" PRId64, fd, (int)pos, semihosting->result);
  if (semihosting->result == pos)
  semihosting->result = 0;
@@ -1383,7 +1389,6 @@ int semihosting_common(struct target *target)
  return retval;
  }
  semihosting->result = semihosting_write(semihosting, fd, buf, len);
- semihosting->sys_errno = errno;
  LOG_DEBUG("write(%d, 0x%" PRIx64 ", %zu)=%" PRId64,
  fd,
  addr,
@@ -1671,7 +1676,6 @@ static int semihosting_common_fileio_end(struct target *target, int result,
  semihosting->hit_fileio = false;
 
  semihosting->result = result;
- semihosting->sys_errno = fileio_errno;
 
  /*
  * Some fileio results do not match up with what the semihosting
@@ -1693,6 +1697,17 @@ static int semihosting_common_fileio_end(struct target *target, int result,
  break;
  }
 
+ bool fileio_failed = false;
+ if (semihosting->op == SEMIHOSTING_SYS_ISTTY)
+ fileio_failed = (semihosting->result == 0);
+ else if (semihosting->op == SEMIHOSTING_SYS_RENAME)
+ fileio_failed = (semihosting->result != 0);
+ else
+ fileio_failed = (semihosting->result == -1);
+
+ if (fileio_failed)
+ semihosting->sys_errno = fileio_errno;
+
  return semihosting->post_result(target);
 }