From 06d50155ac0bd079bfca0f5728346d8beeb205f2 Mon Sep 17 00:00:00 2001
From: sotech117 <michael_foiani@brown.edu>
Date: Tue, 14 May 2024 03:19:46 +0000
Subject: weenix fixes

---
 kernel/api/syscall.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

(limited to 'kernel/api/syscall.c')

diff --git a/kernel/api/syscall.c b/kernel/api/syscall.c
index 467b7d6..7c76e51 100644
--- a/kernel/api/syscall.c
+++ b/kernel/api/syscall.c
@@ -77,11 +77,14 @@ static long sys_read(read_args_t *args)
     ERROR_OUT_RET(ret);
 
     // Allocate a temporary buffer (a page-aligned block of n pages that are enough space to store the number of bytes to read)
-    size_t size_in_pages = (kargs.nbytes + PAGE_SIZE - 1) / PAGE_SIZE;
-    void *addr = (void *)page_alloc_n(size_in_pages);
+    size_t size_in_pages = 0;
+    while(++size_in_pages * PAGE_SIZE < kargs.nbytes)
+        ;
+    void *addr = page_alloc_n(size_in_pages);
     if (!addr)
     {
-        ERROR_OUT_RET(-ENOMEM);
+        ret = -ENOMEM;
+        ERROR_OUT_RET(ret);
     }
 
     // Call do_read() with the buffer and then copy the buffer to the userland args after the system call
@@ -100,7 +103,7 @@ static long sys_read(read_args_t *args)
     }
 
     // copy the buffer to the userland args after the system call
-    ret = copy_to_user(kargs.buf, addr, ret);
+    ret = copy_to_user(kargs.buf, addr, kargs.nbytes);
     // if ret < 0, free the temporary buffer and return -1
     if (ret < 0)
     {
@@ -132,7 +135,9 @@ static long sys_write(write_args_t *args)
     ERROR_OUT_RET(ret);
 
     // Allocate a temporary buffer (a page-aligned block of n pages that are enough space to store the number of bytes to write)
-    size_t size_in_pages = (kargs.nbytes + PAGE_SIZE - 1) / PAGE_SIZE;
+    size_t size_in_pages = 0;
+    while(++size_in_pages * PAGE_SIZE < kargs.nbytes)
+        ;
     void *addr = (void *)page_alloc_n(size_in_pages);
     if (!addr)
     {
@@ -187,10 +192,9 @@ static long sys_getdents(getdents_args_t *args)
         ERROR_OUT_RET(-EINVAL);
     }
 
-    size_t count_read = 0;
-    
-    // iterate over the directory entries
-    while (count_read * sizeof(dirent_t) <= kargs.count)
+    // iterate over the directory entries to get the number of dirs
+    size_t num_dirs = 0;
+    while (num_dirs * sizeof(dirent_t) < kargs.count)
     {
         // read count / sizeof(dirent_t) directory entries into the provided dirp and call do_getdent
         dirent_t d;
@@ -209,13 +213,13 @@ static long sys_getdents(getdents_args_t *args)
         }
 
         // copy the dirent_t to the userland args after the system call
-        ret = copy_to_user(kargs.dirp + count_read, &d, sizeof(dirent_t));
+        ret = copy_to_user(kargs.dirp + num_dirs, &d, sizeof(dirent_t));
         ERROR_OUT_RET(ret); // error check
 
-        count_read++;
+        num_dirs++;
     }
 
-    return count_read * sizeof(dirent_t);
+    return num_dirs * sizeof(dirent_t);
 }
 
 #ifdef __MOUNTING__
@@ -868,4 +872,4 @@ static long syscall_dispatch(size_t sysnum, uintptr_t args, regs_t *regs)
         curthr->kt_errno = ENOSYS;
         return -1;
     }
-}
+}
\ No newline at end of file
-- 
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