libc: Add (v)fprintf and make (v)printf use that

Let's free libc of console_write!

apps/init.c

@@ -34,5 +34,5 @@ int main()
     stdout = fopen("/dev/console", "w");
     stderr = fopen("/dev/console", "w");
 
-    fputs("Hello, world!", stderr);
+    fprintf(stderr, "init is running as PID %d\n", getpid());
 }

libc/include/stdio.h

@@ -84,8 +84,11 @@ extern "C"
 
     void setbuf(FILE*, char*);
 
-    int fprintf(FILE*, const char*, ...);
-    int vfprintf(FILE*, const char*, va_list);
+    /* Write formatted output to a file. */
+    int fprintf(FILE* stream, const char* format, ...);
+
+    /* Write formatted output to a file. */
+    int vfprintf(FILE* stream, const char* format, va_list ap);
 
     /* Write formatted output into a buffer. */
     int sprintf(char* buf, const char* format, ...);
@@ -99,15 +102,15 @@ extern "C"
     /* Write up to max bytes of formatted output into a buffer. */
     int vsnprintf(char*, size_t, const char*, va_list);
 
+    /* Write formatted output to standard output. */
+    int vprintf(const char*, va_list ap);
+
     /* Write formatted output to standard output. */
     int printf(const char*, ...);
 
     /* Write a string followed by a newline to standard output. */
     int puts(const char* s);
 
-    /* Output a message to the console. */
-    int console_write(const char* msg, size_t size);
-
     /* Write an error message to standard error. */
     void perror(const char* s);
 

libc/src/stdio.cpp

@@ -30,12 +30,6 @@ static int fopen_parse_mode(const char* mode)
 
 extern "C"
 {
-    int console_write(const char* str, size_t size)
-    {
-        long rc = syscall(SYS_console_write, str, size);
-        __errno_return(rc, int);
-    }
-
     FILE* fopen(const char* path, const char* mode)
     {
         int flags;
@@ -231,19 +225,46 @@ extern "C"
         return rc;
     }
 
+    int vfprintf(FILE* stream, const char* format, va_list ap)
+    {
+        usize rc = cstyle_format(
+                       format,
+                       [](char c, void* f) -> Result<void> {
+                           int rc = fputc(c, (FILE*)f);
+                           if (rc == EOF) return err(errno);
+                           return {};
+                       },
+                       stream, ap)
+                       .value_or(-1);
+
+        if (rc == (usize)-1) return -1;
+
+        return (int)rc;
+    }
+
+    int fprintf(FILE* stream, const char* format, ...)
+    {
+        va_list ap;
+        va_start(ap, format);
+
+        int rc = vfprintf(stream, format, ap);
+
+        va_end(ap);
+
+        return rc;
+    }
+
+    int vprintf(const char* format, va_list ap)
+    {
+        return vfprintf(stdout, format, ap);
+    }
+
     int printf(const char* format, ...)
     {
         va_list ap;
         va_start(ap, format);
 
-        int rc = (int)cstyle_format(
-                     format,
-                     [](char c, void*) -> Result<void> {
-                         console_write(&c, 1);
-                         return {};
-                     },
-                     nullptr, ap)
-                     .value();
+        int rc = vfprintf(stdout, format, ap);
 
         va_end(ap);
 
@@ -252,30 +273,22 @@ extern "C"
 
     int puts(const char* s)
     {
-        if (console_write(s, strlen(s)) < 0) return -1;
-        if (console_write("\n", 1) < 0) return -1;
+        if (fputs(s, stdout) < 0) return -1;
+        if (putchar('\n') == EOF) return -1;
 
         return 0;
     }
 
     void perror(const char* s)
     {
-        // FIXME: Output to stderr when available.
         int err = errno;
-        if (s && *s) printf("%s: ", s);
-        printf("%s\n", strerror(err));
+        if (s && *s) fprintf(stderr, "%s: ", s);
+        fprintf(stderr, "%s\n", strerror(err));
     }
 }
 
 void debug_log_impl(const char* format, va_list ap)
 {
-    cstyle_format(
-        format,
-        [](char c, void*) -> Result<void> {
-            console_write(&c, 1);
-            return {};
-        },
-        nullptr, ap)
-        .value();
-    console_write("\n", 1);
+    vfprintf(stderr, format, ap);
+    fputc('\n', stderr);
 }