Basic file operations not working as expected when using SPIFFS

[parkersnable]

Hi,

I am currently building a ESP-IDF project using SPIFFS to store various files.

It's mostly going as expected, but I noticed some anomalies.

Reading and writing the files with fopen, fread and fwrite works fine.

While implementing a initial test to check if the file exists and write a blank file if it doesn't I realized, that the access() function always returns -1 to signal the file does not exist. I literally open it with fopen in read mode and the pointer is not NULL, still access returns an error.

Don't I have the permission to check for existence?

Here is the code in question:

Code: [Select all] [Expand/Collapse]

1. ESP_LOGI(TAG, "Testing file access for: %s", path);
2. FILE* test = fopen(path, "r");
3. if (test == NULL) {
4.     ESP_LOGI(TAG, "cant read file");
5. }
6. fclose(test);
7. if (access(path, F_OK) == -1) {
8.     // The log file does not exist, so initialize it with a base structure
9.     FILE* file = fopen(path, "wb");
10.     if (file == NULL) {
11.         ESP_LOGE(TAG, "Failed to create file: %s", path);
12.         return ESP_FAIL;
13.     }
14.     else {
15.         ESP_LOGI(TAG, "file created: %s", path);
16.     }
17.     if (fwrite(data, size, 1, file) != 1) {
18.         ESP_LOGE(TAG, "Failed to write init structure to file: %s", path);
19.         fclose(file);
20.         return ESP_FAIL;
21.     }
22.     else {
23.         ESP_LOGI(TAG, "wrote data to file: %s", path);
24.     }
25.  
26.     fclose(file);
27. }

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[pcoueffin]

Signed up to report that access() works for me in Dec of 2023. ESP32-C2 using espidf on platformio.

I initially thought I had this problem but it turns out that prepending the mountpoint to the filename was important.