libc: Add getline() and getdelim()

apps/su.cpp

@@ -33,7 +33,7 @@ char* getpass()
         return nullptr;
     }
 
-    static char buf[1024];
+    static char buf[BUFSIZ];
     char* rc = fgets(buf, sizeof(buf), stdin);
 
     restore_terminal();

libc/include/stdio.h

@@ -26,6 +26,8 @@ extern FILE* stderr;
 #define stdout stdout
 #define stderr stderr
 
+#define BUFSIZ 1024
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -96,6 +98,12 @@ extern "C"
     /* Read a line from stream. */
     char* fgets(char* buf, size_t size, FILE* stream);
 
+    /* Read a line from stream and store it in a dynamically-allocated buffer. */
+    ssize_t getline(char** linep, size_t* n, FILE* stream);
+
+    /* Read a line from stream and store it in a dynamically-allocated buffer. */
+    ssize_t getdelim(char** linep, size_t* n, int delim, FILE* stream);
+
     /* Clear the error and end-of-file indicators in stream. */
     void clearerr(FILE* stream);
 

libc/src/stdio.cpp

@@ -236,6 +236,66 @@ extern "C"
         return buf;
     }
 
+    ssize_t getline(char** linep, size_t* n, FILE* stream)
+    {
+        return getdelim(linep, n, '\n', stream);
+    }
+
+    ssize_t getdelim(char** linep, size_t* n, int delim, FILE* stream)
+    {
+        if (!n || !linep)
+        {
+            errno = EINVAL;
+            return -1;
+        }
+
+        char* buf = *linep;
+        size_t size = *n;
+        size_t len = 0;
+
+        if (!buf)
+        {
+            buf = (char*)malloc(BUFSIZ);
+            size = BUFSIZ;
+            if (!buf) return -1;
+            *linep = buf;
+            *n = size;
+        }
+
+        while (1)
+        {
+            int c = fgetc(stream);
+            if (c == EOF) break;
+
+            if (len == size)
+            {
+                buf = (char*)realloc(buf, size + 64);
+                size += 64;
+                if (!buf) return -1;
+                *linep = buf;
+                *n = size;
+            }
+
+            buf[len++] = (char)c;
+            if (c == delim) break;
+        }
+
+        if (len == 0) return -1;
+
+        if (len == size)
+        {
+            buf = (char*)realloc(buf, size + 16);
+            size += 16;
+            if (!buf) return -1;
+            *linep = buf;
+            *n = size;
+        }
+
+        buf[len] = '\0';
+
+        return (ssize_t)len;
+    }
+
     void clearerr(FILE* stream)
     {
         stream->_eof = stream->_err = 0;

libc/src/strftime.cpp

@@ -36,7 +36,7 @@ static bool try_format(strftime_state& state, const char* format, ...)
     va_list ap;
     va_start(ap, format);
 
-    char buf[1024];
+    char buf[BUFSIZ];
     vsnprintf(buf, sizeof(buf), format, ap);
 
     va_end(ap);

libc/src/unistd.cpp

@@ -4,6 +4,7 @@
 #include <luna/Vector.h>
 #include <stdarg.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
@@ -347,17 +348,17 @@ extern "C"
         }
         else
         {
-            buf = (char*)malloc(1024);
+            buf = (char*)malloc(BUFSIZ);
             if (!buf) return nullptr;
 
-            ssize_t rc = __getcwd_wrapper(buf, 1024);
+            ssize_t rc = __getcwd_wrapper(buf, BUFSIZ);
             if (rc < 0)
             {
                 free(buf);
                 return nullptr;
             }
 
-            if (rc > 1024)
+            if (rc > BUFSIZ)
             {
                 free(buf);