Add the files

1 files changed, 149 insertions, 0 deletions

diff --git a/src/detection/packages/packages_nix.c b/src/detection/packages/packages_nix.c
new file mode 100644
index 0000000..d1cc264
--- /dev/null
+++ b/src/detection/packages/packages_nix.c
@@ -0,0 +1,149 @@
+#include "packages.h"
+#include "common/io.h"
+#include "common/processing.h"
+#include "common/strutil.h"
+
+static bool isValidNixPkg(FFstrbuf* pkg) {
+    if (!ffPathExists(pkg->chars, FF_PATHTYPE_DIRECTORY)) {
+        return false;
+    }
+
+    ffStrbufSubstrAfterLastC(pkg, '/');
+    if (
+        ffStrbufStartsWithS(pkg, "nixos-system-nixos-") ||
+        ffStrbufEndsWithS(pkg, "-doc") ||
+        ffStrbufEndsWithS(pkg, "-man") ||
+        ffStrbufEndsWithS(pkg, "-info") ||
+        ffStrbufEndsWithS(pkg, "-dev") ||
+        ffStrbufEndsWithS(pkg, "-bin")) {
+        return false;
+    }
+
+    enum { START,
+        DIGIT,
+        DOT,
+        MATCH } state = START;
+
+    for (uint32_t i = 0; i < pkg->length; i++) {
+        char c = pkg->chars[i];
+        switch (state) {
+            case START:
+                if (ffCharIsDigit(c)) {
+                    state = DIGIT;
+                }
+                break;
+            case DIGIT:
+                if (ffCharIsDigit(c)) {
+                    continue;
+                }
+                if (c == '.') {
+                    state = DOT;
+                } else {
+                    state = START;
+                }
+                break;
+            case DOT:
+                if (ffCharIsDigit(c)) {
+                    state = MATCH;
+                } else {
+                    state = START;
+                }
+                break;
+            case MATCH:
+                break;
+        }
+    }
+
+    return state == MATCH;
+}
+
+static bool checkNixCache(FFstrbuf* cacheDir, FFstrbuf* hash, uint32_t* count) {
+    if (!ffPathExists(cacheDir->chars, FF_PATHTYPE_FILE)) {
+        return false;
+    }
+
+    FF_STRBUF_AUTO_DESTROY cacheContent = ffStrbufCreate();
+    if (!ffReadFileBuffer(cacheDir->chars, &cacheContent)) {
+        return false;
+    }
+
+    // Format: <hash>\n<count>
+    uint32_t split = ffStrbufFirstIndexC(&cacheContent, '\n');
+    if (split == cacheContent.length) {
+        return false;
+    }
+
+    ffStrbufSetNS(hash, split, cacheContent.chars);
+    *count = (uint32_t) atoi(cacheContent.chars + split + 1);
+
+    return true;
+}
+
+static bool writeNixCache(FFstrbuf* cacheDir, FFstrbuf* hash, uint32_t count) {
+    FF_STRBUF_AUTO_DESTROY cacheContent = ffStrbufCreateCopy(hash);
+    ffStrbufAppendF(&cacheContent, "\n%u", count);
+    return ffWriteFileBuffer(cacheDir->chars, &cacheContent);
+}
+
+static uint32_t getNixPackagesImpl(char* path) {
+    // Nix detection is kinda slow, so we only do it if the dir exists
+    if (!ffPathExists(path, FF_PATHTYPE_DIRECTORY)) {
+        return 0;
+    }
+
+    FF_STRBUF_AUTO_DESTROY cacheDir = ffStrbufCreateCopy(&instance.state.platform.cacheDir);
+    ffStrbufEnsureEndsWithC(&cacheDir, '/');
+    ffStrbufAppendS(&cacheDir, "fastfetch/packages/nix");
+    ffStrbufAppendS(&cacheDir, path);
+
+    // Check the hash first to determine if we need to recompute the count
+    FF_STRBUF_AUTO_DESTROY hash = ffStrbufCreateA(64);
+    FF_STRBUF_AUTO_DESTROY cacheHash = ffStrbufCreateA(64);
+    uint32_t count = 0;
+
+    ffProcessAppendStdOut(&hash, (char* const[]) { "nix-store", "--query", "--hash", path, NULL });
+
+    if (checkNixCache(&cacheDir, &cacheHash, &count) && ffStrbufEqual(&hash, &cacheHash)) {
+        return count;
+    }
+
+    // Cache is invalid, recompute the count
+    count = 0;
+
+    // Implementation based on bash script from here:
+    // https://github.com/fastfetch-cli/fastfetch/issues/195#issuecomment-1191748222
+
+    FF_STRBUF_AUTO_DESTROY output = ffStrbufCreateA(1024);
+
+    ffProcessAppendStdOut(&output, (char* const[]) { "nix-store", "--query", "--requisites", path, NULL });
+
+    uint32_t lineLength = 0;
+    for (uint32_t i = 0; i < output.length; i++) {
+        if (output.chars[i] != '\n') {
+            lineLength++;
+            continue;
+        }
+
+        output.chars[i] = '\0';
+        FFstrbuf line = {
+            .allocated = 0,
+            .length = lineLength,
+            .chars = output.chars + i - lineLength
+        };
+        if (isValidNixPkg(&line)) {
+            count++;
+        }
+        lineLength = 0;
+    }
+
+    writeNixCache(&cacheDir, &hash, count);
+    return count;
+}
+
+uint32_t ffPackagesGetNix(FFstrbuf* baseDir, const char* dirname) {
+    uint32_t baseDirLength = baseDir->length;
+    ffStrbufAppendS(baseDir, dirname);
+    uint32_t num_elements = getNixPackagesImpl(baseDir->chars);
+    ffStrbufSubstrBefore(baseDir, baseDirLength);
+    return num_elements;
+}