usr: libc: Implement fgets()

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 75 insertions, 0 deletions

diff --git a/lib/libc/include/stdio.h b/lib/libc/include/stdio.h
index 708f200..7d8279d 100644
--- a/lib/libc/include/stdio.h
+++ b/lib/libc/include/stdio.h
@@ -74,6 +74,8 @@ __BEGIN_DECLS
 
 size_t fread(void *__restrict ptr, size_t size, size_t n, FILE *__restrict stream);
 size_t fwrite(const void *__restrict ptr, size_t size, size_t n, FILE *__restrict stream);
+char *fgets(char *__restrict s, int size, FILE *__restrict stream);
+
 FILE *fopen(const char *__restrict path, const char *__restrict mode);
 int fclose(FILE *stream);
 
diff --git a/lib/libc/src/stdio/fgets.c b/lib/libc/src/stdio/fgets.c
new file mode 100644
index 0000000..fdaad84
--- /dev/null
+++ b/lib/libc/src/stdio/fgets.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+
+extern size_t __stdio_read(void *__restrict ptr, size_t size, FILE *__restrict stream);
+
+char *
+fgets(char *__restrict s, int size, FILE *__restrict stream)
+{
+    size_t count;
+    uint8_t tmp;
+    int idx = 0;
+    char c;
+
+    if (stream == NULL) {
+        return NULL;
+    }
+
+    for (;;)  {
+        count = __stdio_read(&tmp, sizeof(tmp), stream);
+        if (count <= 0 && idx == 0) {
+            s[idx] = '\0';
+            return NULL;
+        }
+        if (count <= 0 && idx > 0) {
+            s[idx] = '\0';
+            break;
+        }
+
+        c = (char)tmp;
+        s[idx++] = c;
+
+        if (c == '\n') {
+            s[idx] = '\0';
+            break;
+        }
+
+        /* Did we read the entire line? */
+        if (idx >= size - 1) {
+            return s;
+        }
+    }
+
+    return s;
+}