feat: file descriptor and proper stdio

4 files changed, 106 insertions, 35 deletions

diff --git a/user/chat.c b/user/chat.c
new file mode 100644
index 0000000..67bc727
--- /dev/null
+++ b/user/chat.c
@@ -0,0 +1,33 @@
+#include "user.h"
+
+void _start(const char* arg, unsigned long arglen)
+{
+    if (arglen == 0)
+    {
+        put("usage: run chat <path>\n");
+        sys_exit(1);
+    }
+
+    char path[128];
+    unsigned long i = 0;
+    for (; i < arglen && i < sizeof(path) - 1; i++)
+        path[i] = arg[i];
+    path[i] = 0;
+
+    long fd = sys_open(path, 0);
+    if (fd < 0)
+    {
+        put("chat: ");
+        put(path);
+        put(": cannot open\n");
+        sys_exit(1);
+    }
+
+    char buffer[256];
+    long n;
+    while ((n = sys_read(fd, buffer, sizeof(buffer))) > 0)
+        sys_write(1, buffer, (unsigned long)n);
+
+    sys_close(fd);
+    sys_exit(0);
+}
diff --git a/user/hexview.c b/user/hexview.c
index c211b44..5eac27c 100644
--- a/user/hexview.c
+++ b/user/hexview.c
@@ -5,7 +5,7 @@ static const char HEX[] = "0123456789abcdef";
 static void put_hex8(unsigned char byte)
 {
     char digits[2] = { HEX[byte >> 4], HEX[byte & 15] };
-    sys_write(digits, 2);
+    sys_write(1, digits, 2);
 }
 
 static void put_hex32(unsigned long value)
@@ -13,7 +13,7 @@ static void put_hex32(unsigned long value)
     char digits[8];
     for (int nibble = 0; nibble < 8; nibble++)
         digits[nibble] = HEX[(value >> ((7 - nibble) * 4)) & 15];
-    sys_write(digits, 8);
+    sys_write(1, digits, 8);
 }
 
 #define PAGE 256
@@ -67,7 +67,7 @@ void _start(const char* arg, unsigned long arglen)
                 if (row + column < count)
                 {
                     put_hex8((unsigned char)buffer[row + column]);
-                    sys_write(" ", 1);
+                    sys_write(1, " ", 1);
                 }
                 else
                     put("   ");
@@ -78,19 +78,19 @@ void _start(const char* arg, unsigned long arglen)
             {
                 char character = buffer[row + column];
                 if (character >= 32 && character < 127)
-                    sys_write(&character, 1);
+                    sys_write(1, &character, 1);
                 else
-                    sys_write(".", 1);
+                    sys_write(1, ".", 1);
             }
             put("\n");
         }
 
         put("[n]ext [p]rev [q]uit (or up/down arrows) > ");
-        char key = (char)sys_read();
+        char key = (char)get_char();
         if (key == 27) // ESC
         {
-            sys_read();
-            char final = (char)sys_read();
+            get_char();
+            char final = (char)get_char();
             if (final == 'A')
                 key = 'p';
             else if (final == 'B')
diff --git a/user/save.c b/user/save.c
index b3664f4..48e1930 100644
--- a/user/save.c
+++ b/user/save.c
@@ -2,23 +2,30 @@
 
 void _start(const char* arg, unsigned long arglen)
 {
-    if (arglen == 0 || arglen >= 64)
+    if (arglen == 0 || arglen >= 120)
     {
         put("usage: run save <path>\n");
         sys_exit(1);
     }
 
-    char name[64];
+    char name[128];
     for (unsigned long i = 0; i < arglen; i++)
         name[i] = arg[i];
     name[arglen] = 0;
 
+    long fd = sys_open(name, O_CREAT | O_TRUNC | O_WRONLY);
+    if (fd < 0)
+    {
+        put("save: ");
+        put(name);
+        put(": cannot open\n");
+        sys_exit(1);
+    }
+
     put("saving to ");
     put(name);
     put(" -- type lines, a single . saves\n");
 
-    char buffer[4096];
-    int length = 0;
     for (;;)
     {
         char line[256];
@@ -26,20 +33,13 @@ void _start(const char* arg, unsigned long arglen)
         put("\n");
         if (n == 1 && line[0] == '.')
             break;
-        for (int i = 0; i < n && length < 4000; i++)
-            buffer[length++] = line[i];
-        if (length < 4000)
-            buffer[length++] = '\n';
+        sys_write(fd, line, (unsigned long)n);
+        sys_write(fd, "\n", 1);
     }
 
-    if (sys_fs_write(name, buffer, (unsigned long)length))
-    {
-        put("saved ");
-        put(name);
-        put("\n");
-    }
-    else
-        put("write failed\n");
-
+    sys_close(fd);
+    put("saved ");
+    put(name);
+    put("\n");
     sys_exit(0);
 }
diff --git a/user/user.h b/user/user.h
index 635dc86..34710ac 100644
--- a/user/user.h
+++ b/user/user.h
@@ -1,16 +1,44 @@
-// shared syscall stubs
+#define SEEK_SET 0
+#define SEEK_CUR 1
+#define SEEK_END 2
 
-static long sys_write(const char* buffer, unsigned long length)
+#define O_WRONLY 1
+#define O_CREAT  0x40
+#define O_TRUNC  0x200
+#define O_APPEND 0x400
+
+static long sys_write(long fd, const char* buffer, unsigned long length)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(1L), "D"(fd), "S"(buffer), "d"(length) : "memory");
+    return result;
+}
+
+static long sys_read(long fd, char* buffer, unsigned long length)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(2L), "D"(fd), "S"(buffer), "d"(length) : "memory");
+    return result;
+}
+
+static long sys_open(const char* path, long flags)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(7L), "D"(path), "S"(flags) : "memory");
+    return result;
+}
+
+static long sys_close(long fd)
 {
     long result;
-    __asm__ volatile("int $0x80" : "=a"(result) : "a"(1L), "D"(buffer), "S"(length) : "memory");
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(8L), "D"(fd) : "memory");
     return result;
 }
 
-static long sys_read(void)
+static long sys_lseek(long fd, long offset, long whence)
 {
     long result;
-    __asm__ volatile("int $0x80" : "=a"(result) : "a"(2L) : "memory");
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(9L), "D"(fd), "S"(offset), "d"(whence) : "memory");
     return result;
 }
 
@@ -52,7 +80,15 @@ static void put(const char* string)
     unsigned long length = 0;
     while (string[length])
         length++;
-    sys_write(string, length);
+    sys_write(1, string, length);
+}
+
+static int get_char(void)
+{
+    char c;
+    if (sys_read(0, &c, 1) <= 0)
+        return -1;
+    return (unsigned char)c;
 }
 
 static int read_line(char* buffer, int max_length)
@@ -60,7 +96,9 @@ static int read_line(char* buffer, int max_length)
     int length = 0;
     for (;;)
     {
-        char character = (char)sys_read();
+        char character;
+        if (sys_read(0, &character, 1) <= 0)
+            break;
         if (character == '\n')
             break;
         if (character == '\b')
@@ -68,14 +106,14 @@ static int read_line(char* buffer, int max_length)
             if (length > 0)
             {
                 length--;
-                sys_write("\b \b", 3);
+                sys_write(1, "\b \b", 3);
             }
             continue;
         }
         if (length < max_length - 1)
         {
             buffer[length++] = character;
-            sys_write(&character, 1);
+            sys_write(1, &character, 1);
         }
     }
     buffer[length] = 0;
@@ -108,5 +146,5 @@ static void put_int(long value)
         buffer[right] = swap;
     }
 
-    sys_write(buffer, length);
+    sys_write(1, buffer, length);
 }