Game crashes if files are in lowercase

[dak151]

Built / compiled the game on Linux Mint 22.1 -- runs great, no problems at all if the game data files are in UPPERCASE.
If files are in lowercase the engine errors with "file not found errors"

cosmo_engine -ep1 -fs -datadir ./ep1 -savedir ./ep1 -gamedir ./ep1
audio_init(): opened=1 times  frequency=22050Hz  format=S16LSB  channels=1
INFO: Game controllers found: 0 Mappings: './ep1/gamecontrollerdb.txt' Count: -1
Failed opening './ep1/COSMO1.VOL'
Error: opening COSMO1.VOL
cosmo_engine: /home/test/cosmo-engine/src/files/vol.c:127: vol_file_open: Assertion `open_vol_file(vol_filename, &vol_file)' failed.
./cca.sh: line 33:  9117 Aborted                 (core dumped) /home/user/Games/Cosmo/cosmo_engine -$ans -fs -datadir ./ep1 -savedir ./ep1 -gamedir ./ep1

Cheers,

[runlevel5]

@dak151 the game engine hardcoded the file to be all uppercase. In theory we could easily adjust the logic to look up case-insensitive file though I do not think the engine should.

FYI

patch -p1 < case-insensitive-files.patch

Subject: [PATCH] Fix case-sensitivity issue for game data files on Linux

On case-sensitive filesystems (Linux), the engine fails to find game data
files when they have lowercase names (e.g., cosmo1.vol instead of COSMO1.VOL).

This patch adds a case-insensitive file open fallback that scans the directory
for a matching filename when the exact match fails. On Windows, where the
filesystem is already case-insensitive, this is a no-op.

---
 src/files/file.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 2 deletions(-)

diff --git a/src/files/file.c b/src/files/file.c
index 78300ab..d693c4b 100644
--- a/src/files/file.c
+++ b/src/files/file.c
@@ -19,8 +19,84 @@
  */
 
 #include <SDL_filesystem.h>
+#include <stdlib.h>
+#include <string.h>
 #include "file.h"
 
+#if defined(__linux__) || defined(__unix__) || defined(__APPLE__)
+#include <dirent.h>
+#include <strings.h>
+#include <libgen.h>
+#define HAVE_CASE_INSENSITIVE_OPEN 1
+#endif
+
+#ifdef HAVE_CASE_INSENSITIVE_OPEN
+/**
+ * Try to open a file with case-insensitive filename matching.
+ * On case-sensitive filesystems (Linux), if the exact filename doesn't exist,
+ * this function will search the directory for a case-insensitive match.
+ * Returns the FILE pointer on success, NULL on failure.
+ */
+static FILE *fopen_case_insensitive(const char *filename, const char *mode) {
+    // First try the exact filename
+    FILE *fp = fopen(filename, mode);
+    if (fp != NULL) {
+        return fp;
+    }
+
+    // Make a copy of the path since dirname/basename may modify it
+    char *path_copy = strdup(filename);
+    char *filename_copy = strdup(filename);
+    if (!path_copy || !filename_copy) {
+        free(path_copy);
+        free(filename_copy);
+        return NULL;
+    }
+
+    char *dir = dirname(path_copy);
+    char *base = basename(filename_copy);
+
+    // Open the directory and search for a case-insensitive match
+    DIR *d = opendir(dir);
+    if (d == NULL) {
+        free(path_copy);
+        free(filename_copy);
+        return NULL;
+    }
+
+    struct dirent *entry;
+    char *matched_name = NULL;
+    while ((entry = readdir(d)) != NULL) {
+        if (strcasecmp(entry->d_name, base) == 0) {
+            matched_name = entry->d_name;
+            break;
+        }
+    }
+
+    if (matched_name != NULL) {
+        // Build the full path with the correctly-cased filename
+        size_t full_path_len = strlen(dir) + strlen(matched_name) + 2;
+        char *full_path = (char *)malloc(full_path_len);
+        if (full_path) {
+            snprintf(full_path, full_path_len, "%s/%s", dir, matched_name);
+            fp = fopen(full_path, mode);
+            free(full_path);
+        }
+    }
+
+    closedir(d);
+    free(path_copy);
+    free(filename_copy);
+
+    return fp;
+}
+#else
+/* On Windows, the filesystem is case-insensitive by default */
+static FILE *fopen_case_insensitive(const char *filename, const char *mode) {
+    return fopen(filename, mode);
+}
+#endif
+
 uint32 calculate_filesize(FILE *fp) {
     uint32 file_length;
 
@@ -49,7 +125,7 @@ const char *get_full_SDL_path(const char *filename) {
 }
 
 bool file_open(const char *filename, const char *mode, File *file) {
-    file->fp = fopen(filename, mode);
+    file->fp = fopen_case_insensitive(filename, mode);
 
     if(file->fp == NULL)
     {
@@ -65,7 +141,7 @@ bool file_open(const char *filename, const char *mode, File *file) {
 }
 
 bool file_open_at_offset(const char *filename, const char *mode, File *file, uint32 offset, uint32 size) {
-    file->fp = fopen(filename, mode);
+    file->fp = fopen_case_insensitive(filename, mode);
 
     if(file->fp == NULL)
     {
-- 
2.39.0