Make sys_write prototype agree with user space, which takes a const void*

Most of this is propagating the const-ness through the myriad write functions.

Make sys_write prototype agree with user space, which takes a const void*
5d6e4065 · Austin Clements · a7d4b8fe · 5d6e4065 · 5d6e4065 · 5d6e4065
--- a/include/file.hh
+++ b/include/file.hh
@@ -14,7 +14,7 @@ struct file : public referenced, public rcu_freed {
  int          stat(struct stat*);
  int          read(char *addr, int n);
  ssize_t      pread(char *addr, size_t n, off_t offset);
-  int          write(char *addr, int n);
+  int          write(const char *addr, int n);

  enum { FD_NONE, FD_PIPE, FD_INODE, FD_SOCKET } type;  

@@ -75,7 +75,7 @@ struct inode : public rcu_freed {

 struct devsw {
  int (*read)(struct inode*, char*, u32, u32);
-  int (*write)(struct inode*, char*, u32, u32);
+  int (*write)(struct inode*, const char*, u32, u32);
  void (*stat)(struct inode*, struct stat*);
 };


--- a/include/kern_c.h
+++ b/include/kern_c.h
@@ -38,7 +38,7 @@ long sys_sbrk(int);
 long sys_nsleep(u64);
 long sys_unlink(const char*);
 long sys_wait(void);
-long sys_write(int, char*, int);
+long sys_write(int, const void*, int);
 long sys_uptime(void);
 long sys_map(uptr, u64);
 long sys_unmap(uptr, u64);

--- a/include/kernel.hh
+++ b/include/kernel.hh
@@ -95,7 +95,7 @@ void            iupdate(struct inode*);
 void            iunlock(struct inode*);
 int             readi(struct inode*, char*, u32, u32);
 void            stati(struct inode*, struct stat*);
-int             writei(struct inode*, char*, u32, u32);
+int             writei(struct inode*, const char*, u32, u32);
 struct inode*   idup(struct inode*);
 struct inode*   nameiparent(inode *cwd, const char*, char*);
 int             dirlink(struct inode*, const char*, u32);
@@ -160,7 +160,7 @@ void            piceoi(void);
 int             pipealloc(struct file**, struct file**);
 void            pipeclose(struct pipe*, int);
 int             piperead(struct pipe*, char*, int);
-int             pipewrite(struct pipe*, char*, int);
+int             pipewrite(struct pipe*, const char*, int);

 // proc.c
 struct proc*    copyproc(struct proc*);
@@ -248,4 +248,3 @@ void trapret(void);
 void threadstub(void);
 void threadhelper(void (*fn)(void *), void *arg);
 void trap(struct trapframe *tf);
-
--- a/include/net.hh
+++ b/include/net.hh
@@ -2,7 +2,7 @@

 void netclose(int sock);
 int netread(int, char *, int);
-int netwrite(int, char *, int);
+int netwrite(int, const char *, int);
 long netsocket(int, int, int);
 long netbind(int, void *, int);
 long netlisten(int, int);

--- a/kernel/console.cc
+++ b/kernel/console.cc
@@ -210,7 +210,7 @@ panic(const char *fmt, ...)
 }

 static int
-consolewrite(struct inode *ip, char *buf, u32 off, u32 n)
+consolewrite(struct inode *ip, const char *buf, u32 off, u32 n)
 {
  int i;


--- a/kernel/file.cc
+++ b/kernel/file.cc
@@ -102,7 +102,7 @@ file::pread(char *addr, size_t n, off_t off)
 }

 int
-file::write(char *addr, int n)
+file::write(const char *addr, int n)
 {
  int r;


--- a/kernel/fs.cc
+++ b/kernel/fs.cc
@@ -569,7 +569,7 @@ readi(struct inode *ip, char *dst, u32 off, u32 n)
 // PAGEBREAK!
 // Write data to inode.
 int
-writei(struct inode *ip, char *src, u32 off, u32 n)
+writei(struct inode *ip, const char *src, u32 off, u32 n)
 {
  u32 tot, m;
  struct buf *bp;

--- a/kernel/net.cc
+++ b/kernel/net.cc
@@ -346,7 +346,7 @@ netclose(int sock)
 }

 int
-netwrite(int sock, char *ubuf, int len)
+netwrite(int sock, const char *ubuf, int len)
 {
  void *kbuf;
  int cc;
@@ -436,7 +436,7 @@ netclose(int sock)
 }

 int
-netwrite(int sock, char *buf, int len)
+netwrite(int sock, const char *buf, int len)
 {
  return -1;
 }

--- a/kernel/pipe.cc
+++ b/kernel/pipe.cc
@@ -81,7 +81,7 @@ pipeclose(struct pipe *p, int writable)

 //PAGEBREAK: 40
 int
-pipewrite(struct pipe *p, char *addr, int n)
+pipewrite(struct pipe *p, const char *addr, int n)
 {
  int i;


--- a/kernel/sampler.cc
+++ b/kernel/sampler.cc
@@ -220,7 +220,7 @@ sampread(struct inode *ip, char *dst, u32 off, u32 n)
 }

 static int
-sampwrite(struct inode *ip, char *buf, u32 off, u32 n)
+sampwrite(struct inode *ip, const char *buf, u32 off, u32 n)
 {
  struct sampconf *conf;


--- a/kernel/spinlock.cc
+++ b/kernel/spinlock.cc
@@ -218,7 +218,7 @@ lockstat_read(struct inode *ip, char *dst, u32 off, u32 n)
 }

 static int
-lockstat_write(struct inode *ip, char *buf, u32 off, u32 n)
+lockstat_write(struct inode *ip, const char *buf, u32 off, u32 n)
 {
  int cmd = buf[0] - '0';


--- a/kernel/sysfile.cc
+++ b/kernel/sysfile.cc
@@ -71,13 +71,13 @@ sys_pread(int fd, void *ubuf, size_t count, off_t offset)
 }

 long
-sys_write(int fd, char *p, int n)
+sys_write(int fd, const void *p, int n)
 {
  sref<file> f;

  if (!getfile(fd, &f) || argcheckptr(p, n) < 0)
    return -1;
-  return f->write(p, n);
+  return f->write(static_cast<const char*>(p), n);
 }

 long