tpm: Add tpm_buf_read_{u8,u16,u32}

[linux-2.6-block.git] / drivers / char / tpm / tpm-buf.c

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index d679dc1cecc7958fc22d8e0e239bdbf361fa9e54..cc14fa3fd8c2a307b185b02faad9f823cd7ee89c 100644 (file)
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -108,7 +108,7 @@ void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
                return;
 
        if ((buf->length + new_length) > PAGE_SIZE) {
-               WARN(1, "tpm_buf: overflow\n");
+               WARN(1, "tpm_buf: write overflow\n");
                buf->flags |= TPM_BUF_OVERFLOW;
                return;
        }
@@ -144,3 +144,80 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
        tpm_buf_append(buf, (u8 *)&value2, 4);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
+
+/**
+ * tpm_buf_read() - Read from a TPM buffer
+ * @buf:       &tpm_buf instance
+ * @offset:    offset within the buffer
+ * @count:     the number of bytes to read
+ * @output:    the output buffer
+ */
+static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void *output)
+{
+       off_t next_offset;
+
+       /* Return silently if overflow has already happened. */
+       if (buf->flags & TPM_BUF_BOUNDARY_ERROR)
+               return;
+
+       next_offset = *offset + count;
+       if (next_offset > buf->length) {
+               WARN(1, "tpm_buf: read out of boundary\n");
+               buf->flags |= TPM_BUF_BOUNDARY_ERROR;
+               return;
+       }
+
+       memcpy(output, &buf->data[*offset], count);
+       *offset = next_offset;
+}
+
+/**
+ * tpm_buf_read_u8() - Read 8-bit word from a TPM buffer
+ * @buf:       &tpm_buf instance
+ * @offset:    offset within the buffer
+ *
+ * Return: next 8-bit word
+ */
+u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset)
+{
+       u8 value;
+
+       tpm_buf_read(buf, offset, sizeof(value), &value);
+
+       return value;
+}
+EXPORT_SYMBOL_GPL(tpm_buf_read_u8);
+
+/**
+ * tpm_buf_read_u16() - Read 16-bit word from a TPM buffer
+ * @buf:       &tpm_buf instance
+ * @offset:    offset within the buffer
+ *
+ * Return: next 16-bit word
+ */
+u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset)
+{
+       u16 value;
+
+       tpm_buf_read(buf, offset, sizeof(value), &value);
+
+       return be16_to_cpu(value);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_read_u16);
+
+/**
+ * tpm_buf_read_u32() - Read 32-bit word from a TPM buffer
+ * @buf:       &tpm_buf instance
+ * @offset:    offset within the buffer
+ *
+ * Return: next 32-bit word
+ */
+u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset)
+{
+       u32 value;
+
+       tpm_buf_read(buf, offset, sizeof(value), &value);
+
+       return be32_to_cpu(value);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_read_u32);