From 18b8205f3984bff211131f82e4c0a1e33886ea64 Mon Sep 17 00:00:00 2001
From: znone <glyc@sina.com.cn>
Date: Tue, 27 Aug 2019 12:35:52 +0000
Subject: [PATCH] 提供以标准流的方式直接操纵ODBC的BLOB字段
---
include/qtl_mysql.hpp | 213 +++++------------------------------------------------
1 files changed, 20 insertions(+), 193 deletions(-)
diff --git a/include/qtl_mysql.hpp b/include/qtl_mysql.hpp
index b532588..834e3c1 100644
--- a/include/qtl_mysql.hpp
+++ b/include/qtl_mysql.hpp
@@ -218,7 +218,7 @@
std::string m_errmsg;
};
-class blobbuf : public std::streambuf
+class blobbuf : public qtl::blobbuf
{
public:
blobbuf() : m_stmt(nullptr), m_field(0)
@@ -226,10 +226,7 @@
}
blobbuf(const blobbuf&) = default;
blobbuf& operator=(const blobbuf&) = default;
- virtual ~blobbuf()
- {
- overflow();
- }
+ virtual ~blobbuf() { overflow(); }
void open(MYSQL_STMT* stmt, int field, const binder& b, std::ios_base::openmode mode)
{
@@ -242,211 +239,41 @@
m_stmt = stmt;
m_field = field;
m_binder = b;
- size_t bufsize;
if (b.length) m_size = *b.length;
- if (m_size > 0)
- bufsize = std::min<size_t>(blob_buffer_size, m_size);
- else
- bufsize = blob_buffer_size;
- if (mode&std::ios_base::in)
- {
- m_buf.resize(bufsize);
- m_pos = 0;
- setg(m_buf.data(), m_buf.data(), m_buf.data());
- }
- else if (mode&std::ios_base::out)
- {
- m_buf.resize(bufsize);
- m_pos = 0;
- setp(m_buf.data(), m_buf.data() + bufsize);
- }
-
+ init_buffer(mode);
}
-protected:
- virtual pos_type seekoff(off_type off, std::ios_base::seekdir dir,
- std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override
- {
- if (which&std::ios_base::in)
- {
- pos_type pos = 0;
- pos = seekoff(m_pos, off, dir);
- return seekpos(pos, which);
- }
- return std::streambuf::seekoff(off, dir, which);
- }
-
- virtual pos_type seekpos(pos_type pos,
- std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override
- {
- if (pos >= m_size)
- return pos_type(off_type(-1));
-
- if (which&std::ios_base::out)
- {
- if (pos < m_pos || pos >= m_pos + off_type(egptr() - pbase()))
- {
- overflow();
- m_pos = pos;
- setp(m_buf.data(), m_buf.data() + m_buf.size());
- }
- else
- {
- pbump(off_type(pos - pabs()));
- }
- }
- else if (which&std::ios_base::in)
- {
- if (pos < m_pos || pos >= m_pos + off_type(epptr() - eback()))
- {
- m_pos = pos;
- setg(m_buf.data(), m_buf.data(), m_buf.data());
- }
- else
- {
- gbump(off_type(pos - gabs()));
- }
- }
- return pos;
- }
-
- virtual std::streamsize showmanyc() override
- {
- return m_size - pabs();
- }
-
- virtual int_type underflow() override
- {
- if (pptr() > pbase())
- overflow();
-
- off_type count = egptr() - eback();
- pos_type next_pos=0;
- if (count == 0 && eback() == m_buf.data())
- {
- setg(m_buf.data(), m_buf.data(), m_buf.data() + m_buf.size());
- count = m_buf.size();
- }
- else
- {
- next_pos = m_pos + pos_type(count);
- }
- if (next_pos >= m_size)
- return traits_type::eof();
-
- count = std::min(count, m_size - next_pos);
- m_binder.buffer = m_buf.data();
- m_binder.buffer_length = count;
- m_pos = next_pos;
- int ret = mysql_stmt_fetch_column(m_stmt, &m_binder, m_field, m_pos);
- switch (ret)
- {
- case 0:
- count = std::min(m_binder.buffer_length, *m_binder.length);
- setg(eback(), eback(), eback() + count);
- return traits_type::to_int_type(*gptr());
- case CR_NO_DATA:
- return traits_type::eof();
- default:
- throw error(mysql_stmt_errno(m_stmt), mysql_stmt_error(m_stmt));
- }
- }
-
- virtual int_type overflow(int_type ch = traits_type::eof()) override
- {
- if (pptr() != pbase())
- {
- size_t count = pptr() - pbase();
- int ret = mysql_stmt_send_long_data(m_stmt, m_field, pbase(), count);
- if (ret != 0)
- throw error(mysql_stmt_errno(m_stmt), mysql_stmt_error(m_stmt));
-
- //auto intersection = interval_intersection(m_pos, egptr() - eback(), m_pos, epptr() - pbase());
- //if (intersection.first != intersection.second)
- //{
- // commit(intersection.first, intersection.second);
- //}
-
- m_pos += count;
- setp(pbase(), epptr());
- }
- if (!traits_type::eq_int_type(ch, traits_type::eof()))
- {
- char_type c = traits_type::to_char_type(ch);
- if (m_pos >= m_size)
- return traits_type::eof();
- int ret = mysql_stmt_send_long_data(m_stmt, m_field, &c, 1);
- if (ret != 0)
- throw error(mysql_stmt_errno(m_stmt), mysql_stmt_error(m_stmt));
-
- //auto intersection = interval_intersection(m_pos, egptr() - eback(), m_pos, 1);
- //if (intersection.first != intersection.second)
- //{
- // eback()[intersection.first - m_pos] = c;
- //}
- m_pos += 1;
-
- }
- return ch;
- }
-
- virtual int_type pbackfail(int_type c = traits_type::eof()) override
- {
- if (gptr() == 0
- || gptr() <= eback()
- || (!traits_type::eq_int_type(traits_type::eof(), c)
- && !traits_type::eq(traits_type::to_char_type(c), gptr()[-1])))
- {
- return (traits_type::eof()); // can't put back, fail
- }
- else
- { // back up one position and store put-back character
- gbump(-1);
- if (!traits_type::eq_int_type(traits_type::eof(), c))
- *gptr() = traits_type::to_char_type(c);
- return (traits_type::not_eof(c));
- }
- }
private:
MYSQL_STMT* m_stmt;
binder m_binder;
int m_field;
- std::vector<char> m_buf;
- pos_type m_size;
- pos_type m_pos; //position in the input sequence
- off_type seekoff(off_type position, off_type off, std::ios_base::seekdir dir)
+protected:
+ virtual bool read_blob(char* buffer, off_type& count, pos_type position) override
{
- off_type result = 0;
- switch (dir)
+ m_binder.buffer = buffer;
+ m_binder.buffer_length = count;
+ int ret = mysql_stmt_fetch_column(m_stmt, &m_binder, m_field, position);
+ switch (ret)
{
- case std::ios_base::beg:
- result = off;
- break;
- case std::ios_base::cur:
- result = position + off;
- break;
- case std::ios_base::end:
- result = m_size - off;
+ case 0:
+ count = std::min(m_binder.buffer_length, *m_binder.length);
+ return true;
+ case CR_NO_DATA:
+ return false;
+ default:
+ throw error(mysql_stmt_errno(m_stmt), mysql_stmt_error(m_stmt));
}
- if (result > m_size)
- result = m_size;
- return result;
}
- pos_type gabs() const // absolute offset of input pointer in blob field
+ virtual void write_blob(const char* buffer, size_t count) override
{
- return m_pos + off_type(gptr() - eback());
- }
-
- pos_type pabs() const // absolute offset of output pointer in blob field
- {
- return m_pos + off_type(pptr() - pbase());
+ int ret = mysql_stmt_send_long_data(m_stmt, m_field, buffer, count);
+ if (ret != 0)
+ throw error(mysql_stmt_errno(m_stmt), mysql_stmt_error(m_stmt));
}
};
-
-typedef std::function<void(std::ostream&)> blob_writer;
class base_statement
{
--
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