Messages in this thread Patch in this message | | | Date | Wed, 24 May 2006 20:45:31 +0100 | From | James Pearson <> | Subject | Re: 4096 byte limit to /proc/PID/environ ? |
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H. Peter Anvin wrote: >> >> I'm not worried about that - more the fact that when I do: >> >> % cat /proc/$$/environ | wc -c >> 4096 >> % env | wc -c >> 7329 >> >> /proc/PID/environ is truncated ... >> > > Funny enough, I was looking at this yesterday. I think there is a > pretty clean solution for it, I just haven't had a chance to attack it > yet.
Having a poke about in fs/proc/, I came up with this - probably isn't pretty or clean, but it works ...
James Pearson
--- ./include/linux/proc_fs.h.dist 2006-05-11 02:56:24.000000000 +0100 +++ ./include/linux/proc_fs.h 2006-05-24 13:43:55.964159897 +0100 @@ -250,7 +250,7 @@ int type; union { int (*proc_get_link)(struct inode *, struct dentry **, struct vfsmount **); - int (*proc_read)(struct task_struct *task, char *page); + int (*proc_read)(struct task_struct *task, char *page, loff_t *pos); } op; struct proc_dir_entry *pde; struct inode vfs_inode; --- ./fs/proc/base.c.dist 2006-05-11 02:56:24.000000000 +0100 +++ ./fs/proc/base.c 2006-05-24 13:54:26.370965292 +0100 @@ -409,15 +409,27 @@ (task->state == TASK_STOPPED || task->state == TASK_TRACED) && \ security_ptrace(current,task) == 0))
-static int proc_pid_environ(struct task_struct *task, char * buffer) +static int proc_pid_environ(struct task_struct *task, char * buffer, loff_t *pos) { int res = 0; + int p = *pos; struct mm_struct *mm = get_task_mm(task); + + /* proc_pid_environ is a 'special case' - the required data could + be larger than a page, so we read sequential chunks of the + environment data into the buffer using the supplied offset */ + if (p < 0) + return -EINVAL; + if (mm) { - unsigned int len = mm->env_end - mm->env_start; + unsigned int len = mm->env_end - (mm->env_start + p); if (len > PAGE_SIZE) len = PAGE_SIZE; - res = access_process_vm(task, mm->env_start, buffer, len, 0); + res = access_process_vm(task, (mm->env_start + p), buffer, len, 0); + /* the calling routine (proc_info_read) needs to know we've + used the offset to read the pid data */ + *pos += res; + if (!ptrace_may_attach(task)) res = -ESRCH; mmput(mm); @@ -425,7 +437,7 @@ return res; }
-static int proc_pid_cmdline(struct task_struct *task, char * buffer) +static int proc_pid_cmdline(struct task_struct *task, char * buffer, loff_t *pos) { int res = 0; unsigned int len; @@ -462,7 +474,7 @@ return res; }
-static int proc_pid_auxv(struct task_struct *task, char *buffer) +static int proc_pid_auxv(struct task_struct *task, char *buffer, loff_t *pos) { int res = 0; struct mm_struct *mm = get_task_mm(task); @@ -486,7 +498,7 @@ * Provides a wchan file via kallsyms in a proper one-value-per-file format. * Returns the resolved symbol. If that fails, simply return the address. */ -static int proc_pid_wchan(struct task_struct *task, char *buffer) +static int proc_pid_wchan(struct task_struct *task, char *buffer, loff_t *pos) { char *modname; const char *sym_name; @@ -506,7 +518,7 @@ /* * Provides /proc/PID/schedstat */ -static int proc_pid_schedstat(struct task_struct *task, char *buffer) +static int proc_pid_schedstat(struct task_struct *task, char *buffer, loff_t *pos) { return sprintf(buffer, "%lu %lu %lu\n", task->sched_info.cpu_time, @@ -517,7 +529,7 @@
/* The badness from the OOM killer */ unsigned long badness(struct task_struct *p, unsigned long uptime); -static int proc_oom_score(struct task_struct *task, char *buffer) +static int proc_oom_score(struct task_struct *task, char *buffer, loff_t *pos) { unsigned long points; struct timespec uptime; @@ -745,16 +757,30 @@ unsigned long page; ssize_t length; struct task_struct *task = proc_task(inode); + loff_t pos = *ppos;
if (count > PROC_BLOCK_SIZE) count = PROC_BLOCK_SIZE; if (!(page = __get_free_page(GFP_KERNEL))) return -ENOMEM;
- length = PROC_I(inode)->op.proc_read(task, (char*)page); + length = PROC_I(inode)->op.proc_read(task, (char*)page, &pos);
- if (length >= 0) - length = simple_read_from_buffer(buf, count, ppos, (char *)page, length); + if (length >= 0) { + if (pos != *ppos) { + /* we are using the buffer to store subsequent sections + of the proc_pid data - so the offset into the buffer + will always be 0 - the offset is used to get the + original data */ + pos = 0; + length = simple_read_from_buffer(buf, count, &pos, (char *)page, length); + /* need to update the 'real' offset into the data we + are reading ... */ + *ppos += length; + } + else + length = simple_read_from_buffer(buf, count, ppos, (char *)page, length); + } free_page(page); return length; } --- ./fs/proc/internal.h.dist 2006-05-11 02:56:24.000000000 +0100 +++ ./fs/proc/internal.h 2006-05-24 13:52:53.568391757 +0100 @@ -32,10 +32,10 @@
extern void create_seq_entry(char *name, mode_t mode, struct file_operations *f); extern int proc_exe_link(struct inode *, struct dentry **, struct vfsmount **); -extern int proc_tid_stat(struct task_struct *, char *); -extern int proc_tgid_stat(struct task_struct *, char *); -extern int proc_pid_status(struct task_struct *, char *); -extern int proc_pid_statm(struct task_struct *, char *); +extern int proc_tid_stat(struct task_struct *, char *, loff_t *); +extern int proc_tgid_stat(struct task_struct *, char *, loff_t *); +extern int proc_pid_status(struct task_struct *, char *, loff_t *); +extern int proc_pid_statm(struct task_struct *, char *, loff_t *);
void free_proc_entry(struct proc_dir_entry *de);
--- ./fs/proc/array.c.dist 2006-05-11 02:56:24.000000000 +0100 +++ ./fs/proc/array.c 2006-05-24 13:43:09.327905203 +0100 @@ -293,7 +293,7 @@ cap_t(p->cap_effective)); }
-int proc_pid_status(struct task_struct *task, char * buffer) +int proc_pid_status(struct task_struct *task, char * buffer, loff_t *pos) { char * orig = buffer; struct mm_struct *mm = get_task_mm(task); @@ -465,17 +465,17 @@ return res; }
-int proc_tid_stat(struct task_struct *task, char * buffer) +int proc_tid_stat(struct task_struct *task, char * buffer, loff_t *pos) { return do_task_stat(task, buffer, 0); }
-int proc_tgid_stat(struct task_struct *task, char * buffer) +int proc_tgid_stat(struct task_struct *task, char * buffer, loff_t *pos) { return do_task_stat(task, buffer, 1); }
-int proc_pid_statm(struct task_struct *task, char *buffer) +int proc_pid_statm(struct task_struct *task, char *buffer, loff_t *pos) { int size = 0, resident = 0, shared = 0, text = 0, lib = 0, data = 0; struct mm_struct *mm = get_task_mm(task); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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