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-rw-r--r--fs/seq_file.c114
1 files changed, 92 insertions, 22 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 4023d6be939b..0cbd0494b79e 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -6,13 +6,29 @@
*/
#include <linux/fs.h>
-#include <linux/module.h>
+#include <linux/export.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/page.h>
+
+/*
+ * seq_files have a buffer which can may overflow. When this happens a larger
+ * buffer is reallocated and all the data will be printed again.
+ * The overflow state is true when m->count == m->size.
+ */
+static bool seq_overflow(struct seq_file *m)
+{
+ return m->count == m->size;
+}
+
+static void seq_set_overflow(struct seq_file *m)
+{
+ m->count = m->size;
+}
+
/**
* seq_open - initialize sequential file
* @file: file we initialize
@@ -92,7 +108,7 @@ static int traverse(struct seq_file *m, loff_t offset)
error = 0;
m->count = 0;
}
- if (m->count == m->size)
+ if (seq_overflow(m))
goto Eoverflow;
if (pos + m->count > offset) {
m->from = offset - pos;
@@ -140,9 +156,21 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
mutex_lock(&m->lock);
+ /*
+ * seq_file->op->..m_start/m_stop/m_next may do special actions
+ * or optimisations based on the file->f_version, so we want to
+ * pass the file->f_version to those methods.
+ *
+ * seq_file->version is just copy of f_version, and seq_file
+ * methods can treat it simply as file version.
+ * It is copied in first and copied out after all operations.
+ * It is convenient to have it as part of structure to avoid the
+ * need of passing another argument to all the seq_file methods.
+ */
+ m->version = file->f_version;
+
/* Don't assume *ppos is where we left it */
if (unlikely(*ppos != m->read_pos)) {
- m->read_pos = *ppos;
while ((err = traverse(m, *ppos)) == -EAGAIN)
;
if (err) {
@@ -152,21 +180,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
m->index = 0;
m->count = 0;
goto Done;
+ } else {
+ m->read_pos = *ppos;
}
}
- /*
- * seq_file->op->..m_start/m_stop/m_next may do special actions
- * or optimisations based on the file->f_version, so we want to
- * pass the file->f_version to those methods.
- *
- * seq_file->version is just copy of f_version, and seq_file
- * methods can treat it simply as file version.
- * It is copied in first and copied out after all operations.
- * It is convenient to have it as part of structure to avoid the
- * need of passing another argument to all the seq_file methods.
- */
- m->version = file->f_version;
/* grab buffer if we didn't have one */
if (!m->buf) {
m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
@@ -232,7 +250,7 @@ Fill:
break;
}
err = m->op->show(m, p);
- if (m->count == m->size || err) {
+ if (seq_overflow(m) || err) {
m->count = offs;
if (likely(err <= 0))
break;
@@ -359,7 +377,7 @@ int seq_escape(struct seq_file *m, const char *s, const char *esc)
*p++ = '0' + (c & 07);
continue;
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
m->count = p - m->buf;
@@ -381,7 +399,7 @@ int seq_printf(struct seq_file *m, const char *f, ...)
return 0;
}
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_printf);
@@ -510,7 +528,7 @@ int seq_bitmap(struct seq_file *m, const unsigned long *bits,
return 0;
}
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_bitmap);
@@ -526,7 +544,7 @@ int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
return 0;
}
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_bitmap_list);
@@ -637,11 +655,63 @@ int seq_puts(struct seq_file *m, const char *s)
m->count += len;
return 0;
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_puts);
+/*
+ * A helper routine for putting decimal numbers without rich format of printf().
+ * only 'unsigned long long' is supported.
+ * This routine will put one byte delimiter + number into seq_file.
+ * This routine is very quick when you show lots of numbers.
+ * In usual cases, it will be better to use seq_printf(). It's easier to read.
+ */
+int seq_put_decimal_ull(struct seq_file *m, char delimiter,
+ unsigned long long num)
+{
+ int len;
+
+ if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
+ goto overflow;
+
+ if (delimiter)
+ m->buf[m->count++] = delimiter;
+
+ if (num < 10) {
+ m->buf[m->count++] = num + '0';
+ return 0;
+ }
+
+ len = num_to_str(m->buf + m->count, m->size - m->count, num);
+ if (!len)
+ goto overflow;
+ m->count += len;
+ return 0;
+overflow:
+ seq_set_overflow(m);
+ return -1;
+}
+EXPORT_SYMBOL(seq_put_decimal_ull);
+
+int seq_put_decimal_ll(struct seq_file *m, char delimiter,
+ long long num)
+{
+ if (num < 0) {
+ if (m->count + 3 >= m->size) {
+ seq_set_overflow(m);
+ return -1;
+ }
+ if (delimiter)
+ m->buf[m->count++] = delimiter;
+ num = -num;
+ delimiter = '-';
+ }
+ return seq_put_decimal_ull(m, delimiter, num);
+
+}
+EXPORT_SYMBOL(seq_put_decimal_ll);
+
/**
* seq_write - write arbitrary data to buffer
* @seq: seq_file identifying the buffer to which data should be written
@@ -657,7 +727,7 @@ int seq_write(struct seq_file *seq, const void *data, size_t len)
seq->count += len;
return 0;
}
- seq->count = seq->size;
+ seq_set_overflow(seq);
return -1;
}
EXPORT_SYMBOL(seq_write);