Merge #257

257: Implement read_dir function and test r=lnicola a=Barugon

Implement a `gdal::vsi::read_dir` function and test.

- [x] I agree to follow the project's [code of conduct](https://github.com/georust/gdal/blob/master/CODE_OF_CONDUCT.md).
- [x] I added an entry to `CHANGES.md` if knowledge of this change could be valuable to users.
---



Co-authored-by: Barugon <barugon@dungeonbox.net>

CHANGES.md

@@ -23,6 +23,10 @@
 
   - <https://github.com/georust/gdal/pull/271>
 
+- Add `gdal::vsi::read_dir` function.
+
+  - <https://github.com/georust/gdal/pull/257>
+
 ## 0.12
 
 - Bump Rust edition to 2021

src/utils.rs

@@ -1,7 +1,7 @@
 use gdal_sys::{self, CPLErr};
 use libc::c_char;
 use std::ffi::{CStr, CString};
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use crate::errors::*;
 
@@ -11,7 +11,23 @@ pub fn _string(raw_ptr: *const c_char) -> String {
 }
 
 pub fn _string_array(raw_ptr: *mut *mut c_char) -> Vec<String> {
-    let mut ret_val: Vec<String> = vec![];
+    _convert_raw_ptr_array(raw_ptr, _string)
+}
+
+pub fn _pathbuf(raw_ptr: *const c_char) -> PathBuf {
+    let c_str = unsafe { CStr::from_ptr(raw_ptr) };
+    c_str.to_string_lossy().into_owned().into()
+}
+
+pub fn _pathbuf_array(raw_ptr: *mut *mut c_char) -> Vec<PathBuf> {
+    _convert_raw_ptr_array(raw_ptr, _pathbuf)
+}
+
+fn _convert_raw_ptr_array<F, R>(raw_ptr: *mut *mut c_char, convert: F) -> Vec<R>
+where
+    F: Fn(*const c_char) -> R,
+{
+    let mut ret_val = Vec::new();
     let mut i = 0;
     unsafe {
         loop {
@@ -23,7 +39,7 @@ pub fn _string_array(raw_ptr: *mut *mut c_char) -> Vec<String> {
             if next.is_null() {
                 break;
             }
-            let value = _string(next);
+            let value = convert(next);
             i += 1;
             ret_val.push(value);
         }

src/vsi.rs

@@ -5,7 +5,31 @@ use std::path::{Path, PathBuf};
 use gdal_sys::{VSIFCloseL, VSIFileFromMemBuffer, VSIFree, VSIGetMemFileBuffer, VSIUnlink};
 
 use crate::errors::{GdalError, Result};
-use crate::utils::{_last_null_pointer_err, _path_to_c_string};
+use crate::utils::{_last_null_pointer_err, _path_to_c_string, _pathbuf_array};
+
+/// Read the file names from a virtual file system with optional recursion.
+pub fn read_dir<P: AsRef<Path>>(path: P, recursive: bool) -> Result<Vec<PathBuf>> {
+    _read_dir(path.as_ref(), recursive)
+}
+
+fn _read_dir(path: &Path, recursive: bool) -> Result<Vec<PathBuf>> {
+    let path = _path_to_c_string(path)?;
+    let data = if recursive {
+        let data = unsafe { gdal_sys::VSIReadDirRecursive(path.as_ptr()) };
+        if data.is_null() {
+            return Err(_last_null_pointer_err("VSIReadDirRecursive"));
+        }
+        data
+    } else {
+        let data = unsafe { gdal_sys::VSIReadDir(path.as_ptr()) };
+        if data.is_null() {
+            return Err(_last_null_pointer_err("VSIReadDir"));
+        }
+        data
+    };
+
+    Ok(_pathbuf_array(data))
+}
 
 /// Creates a new VSIMemFile from a given buffer.
 pub fn create_mem_file<P: AsRef<Path>>(file_name: P, data: Vec<u8>) -> Result<()> {
@@ -277,4 +301,43 @@ mod tests {
             })
         );
     }
+
+    #[test]
+    fn test_vsi_read_dir() {
+        use std::path::Path;
+        let zip_path = Path::new(file!())
+            .parent()
+            .unwrap()
+            .parent()
+            .unwrap()
+            .join("fixtures")
+            .join("test_vsi_read_dir.zip");
+
+        // Concatenate "/vsizip/" prefix.
+        let path = ["/vsizip/", zip_path.to_str().unwrap()].concat();
+
+        // Read without recursion.
+        let expected = [
+            Path::new("folder"),
+            Path::new("File 1.txt"),
+            Path::new("File 2.txt"),
+            Path::new("File 3.txt"),
+        ];
+        let files = read_dir(path.as_str(), false).unwrap();
+        assert_eq!(files, expected);
+
+        // Read with recursion.
+        let expected = [
+            Path::new("folder/"),
+            Path::new("folder/File 4.txt"),
+            Path::new("File 1.txt"),
+            Path::new("File 2.txt"),
+            Path::new("File 3.txt"),
+        ];
+        let files = read_dir(path.as_str(), true).unwrap();
+        assert_eq!(files, expected);
+
+        // Attempting to read without VSI prefix returns error.
+        assert!(read_dir(zip_path, false).is_err());
+    }
 }