From b8ad3ebed5a85fc5022afdbf825fae3d37cb0b97 Mon Sep 17 00:00:00 2001
From: elicn <elichn@gmail.com>
Date: Sun, 4 Feb 2024 20:03:43 +0200
Subject: [PATCH] Revamp POSIX syscalls readv / writev

---
 qiling/os/posix/syscall/uio.py | 85 +++++++++++++++++++++-------------
 1 file changed, 52 insertions(+), 33 deletions(-)

diff --git a/qiling/os/posix/syscall/uio.py b/qiling/os/posix/syscall/uio.py
index 6c8e6e3d..bed58a57 100644
--- a/qiling/os/posix/syscall/uio.py
+++ b/qiling/os/posix/syscall/uio.py
@@ -3,42 +3,61 @@
 # Cross Platform and Multi Architecture Advanced Binary Emulation Framework
 #
 
-from qiling import Qiling
+from __future__ import annotations
+from typing import TYPE_CHECKING, Iterator, Tuple
 
-def ql_syscall_writev(ql: Qiling, fd: int, vec: int, vlen: int):
-    regreturn = 0
-    size_t_len = ql.arch.pointersize
-    iov = ql.mem.read(vec, vlen * size_t_len * 2)
-    ql.log.debug('writev() CONTENT:')
-
-    for i in range(vlen):
-        addr = ql.unpack(iov[i * size_t_len * 2 : i * size_t_len * 2 + size_t_len])
-        l = ql.unpack(iov[i * size_t_len * 2 + size_t_len : i * size_t_len * 2 + size_t_len * 2])
-        regreturn += l
-
-        buf = ql.mem.read(addr, l)
-        ql.log.debug(f'{bytes(buf)}')
-
-        if hasattr(ql.os.fd[fd], 'write'):
-            ql.os.fd[fd].write(buf)
-
-    return regreturn
+from qiling.os.posix.structs import make_iovec
 
 
-def ql_syscall_readv(ql: Qiling, fd: int, vec: int, vlen: int):
-    regreturn = 0
-    size_t_len = ql.arch.pointersize
-    iov = ql.mem.read(vec, vlen * size_t_len * 2)
-    ql.log.debug('readv() CONTENT:')
+if TYPE_CHECKING:
+    from qiling import Qiling
 
-    for i in range(vlen):
-        addr = ql.unpack(iov[i * size_t_len * 2 : i * size_t_len * 2 + size_t_len])
-        l = ql.unpack(iov[i * size_t_len * 2 + size_t_len : i * size_t_len * 2 + size_t_len * 2])
-        regreturn += l
 
-        if hasattr(ql.os.fd[fd], 'read'):
-            data = ql.os.fd[fd].read(l)
-            ql.log.debug(f'{data!r}')
-            ql.mem.write(addr, data)
+def __iter_iovec_array(ql: Qiling, base: int, count: int) -> Iterator[Tuple[int, int]]:
+    """Iterate over an iovec array, yielding one iovec's fields at a time.
+    """
 
-    return regreturn
+    iovec = make_iovec(ql.arch.bits, ql.arch.endian)
+
+    for i in range(count):
+        obj = iovec.load_from(ql.mem, base + i * iovec.sizeof())
+
+        yield (obj.iov_base, obj.iov_len)
+
+
+def ql_syscall_writev(ql: Qiling, fd: int, iov: int, iovcnt: int):
+    ret = 0
+
+    if hasattr(ql.os.fd[fd], 'write'):
+        ql.log.debug('writev CONTENT:')
+
+        for iov_base, iov_len in __iter_iovec_array(ql, iov, iovcnt):
+            data = ql.mem.read(iov_base, iov_len)
+            ql.log.debug(f'  {iov_base = :#x}, {iov_len = :#x} : {bytes(data)}')
+
+            ql.os.fd[fd].write(data)
+            ret += len(data)
+
+    else:
+        ql.log.debug('writev: destination fd is not writeable, no bytes were written')
+
+    return ret
+
+
+def ql_syscall_readv(ql: Qiling, fd: int, iov: int, iovcnt: int):
+    ret = 0
+
+    if hasattr(ql.os.fd[fd], 'read'):
+        ql.log.debug('readv CONTENT:')
+
+        for iov_base, iov_len in __iter_iovec_array(ql, iov, iovcnt):
+            data = ql.os.fd[fd].read(iov_len)
+            ql.log.debug(f'  {iov_base = :#x}, {iov_len = :#x} : {bytes(data)}')
+
+            ql.mem.write(iov_base, data)
+            ret += len(data)
+
+    else:
+        ql.log.debug('readv: source fd is not readable, no bytes were read')
+
+    return ret